Well, upcoming order is still waiting the go-ahead from the finance queen (wifey) but figured I'd get all the details out of the way ahead of time and get some feedback here while I'm waitin. So that said, here's what I currently have penned out for my 2003 GM Option-1 discounted AVy order. Lookin for suggestions, experiences, comments, or heck, even an atta-boy. 
For background on why I made some of the choices below. I plan on doing a little camping and a LOT of Mountain Biking with the truck (ie. light offroad). It won't be my commuter vehicle very often, but better gas mileage is still a plus to me. I don't plan on towing anything heavier than a small pop-up camper trailer in the forseeable future. I live in North Texas where the terrain is FLAT Flat flat. I put thoughts or questions in () below.
THE AVALANCHE
Z71 - 2003 Avalanche Z71 4x4
Light Pewter w/ Dark Charcoal Cladding
(Lighter color hopefully good for Texas heat and Light Pewter doesn't seem to show dirt as fast thought I think the dark cladding might negate that bonus.)
GT4 - 3.73 Axle Ratio
(Better gas mileage and I don't have much in terms of towing needs.)
QJP - P265/70R17 On/Off Road SBR BSW Tires
(EDIT: Picked the Black SideWall (BSW) ones thanks to Flynhigh's comment below, don't like the white letter look. Might try to do aftermarket ~275-285 tall (EDIT: Lowered that 10 also on Flyn's comments) if I can get the dealer to swap 'em and no serious fender work is needed. I will probably twist the torsion bar enough to get ~1" raise in the front if that helps. Also might see if I can find some tires that have "stiffer" sidewalls that I get the impression the 2500s have which helps in their lateral handling. Thoughts there?)
AN3 - ?Leather Reclining Seats with Driver memory
(So wife and I can both drive without constant seat sliding. Don't care about heated seats personally. Not sure yet if I should go with Natural Color Leather to come close to Light Pewter Color outside or with the Charcoal Leather to match the cladding and interior plastic. Not sure if the Charcoal Leather is hotter when sitting in the sun though. Any thoughts there?)
UC6 - Bose 6-Disc CR Changer Stereo
(Nice to have decent sound without having to do it myself.)
PDH - Driver Convenience Pkg
(Adjustable pedals help with short wife and I like the convenience lights/buttons. Not sure I want OnStar and don't think Front Side Airbags a priority in a vehicle that already does great on impacts.)
V54 - Black Roof Luggage Carrier
(Is this the one you need to add roof carrying accessories like the bike carrier? Figured I'd leave off sunroof to try to keep out some of the Texas Heat. I already have one on my Cavalier and don't use it often.)
BVQ - Tubular Chrome Assist Steps
(I think these look much better than running boards though I might consider getting them aftermarket depending on price difference. Nice to have them included in financed price though.)
Z82 - HD Trailering Equipment
(I DEFINATELY want the 2" trailer reciever and wasn't sure I'd get one at all without this.)
THE EXTRAS
- American Racing Custom Wheels
(From the GM Accessories web page http://www.gmgoodwrench.com/accessories/accessdetailAva_174.html. These look pretty kool. What do ya think?)
- Brush/Grill Guard
(Not sure yet if I want the GM one or an aftermarket. Lots look good, but I'd really like whichever one I choose to be able to handle a light bump if necessary without scratching, flaking paint, or setting off the air bags.)
- Side Window Weather Deflectors
(I hear the tape comes loose so thinking I'd prefer the aftermarket ones that attach inside the weatherstripping. Does your window still close fully and shut out wind noise with those?)
- Molded Hood Protector
(Haven't seen one with AVy logo yet, but probably will get the smoke one without logo.)
- Windshield Graphics
(Dunno if I want this on the front, or maybe would look good on the back window?)
- Black-Out Headlight/Taillight covers.
(I REALLY like the slick look on these aftermarket ones. I saw a pic on this site from someone who had them.)
- Custom Molded Splash Guards
(I like the finished look of these but hear they're not suggested for offroading because they can catch/tear and sometimes do cladding damage when they do. I don't think I'll run into that problem where I'll be, but anyone have any experience with that? What kind of terrain are they prone to snagging on? Maybe will notch them intentionally so they break away easier or something.)
- Pickup Box Extender
(I like the look of these and think they'd work well for keeping groceries near the tailgate while driving/stopping. Also looks like a good place to attach a Bike Fork Clamp for carrying bikes inside the bed.)
- Bed Sport Tent
(Think I'll skip on this and stick with a real tent.)
- Vinyl Floor Mats.
(I like the large size, durability to Mtb Mud/Dirt, and Gold Bowtie logo.)
- Second Row Seat Liner
(Gotta keep the seat nice lookin when hauling house fixit stuff from Lowe's and when the dog is in the back.)
- Hot/Cold Beverage Console
(MAYBE. Sure looks nifty though.)
That's about all I can think of at the moment short of getting into some of the Mods I've seen that help both HP and MPG. Those all look like lots of good fun to me. Can't wait to mod a bit but I'll hold off on drooling over those for now.
For background on why I made some of the choices below. I plan on doing a little camping and a LOT of Mountain Biking with the truck (ie. light offroad). It won't be my commuter vehicle very often, but better gas mileage is still a plus to me. I don't plan on towing anything heavier than a small pop-up camper trailer in the forseeable future. I live in North Texas where the terrain is FLAT Flat flat. I put thoughts or questions in () below.
THE AVALANCHE
Z71 - 2003 Avalanche Z71 4x4
Light Pewter w/ Dark Charcoal Cladding
(Lighter color hopefully good for Texas heat and Light Pewter doesn't seem to show dirt as fast thought I think the dark cladding might negate that bonus.)
GT4 - 3.73 Axle Ratio
(Better gas mileage and I don't have much in terms of towing needs.)
QJP - P265/70R17 On/Off Road SBR BSW Tires
(EDIT: Picked the Black SideWall (BSW) ones thanks to Flynhigh's comment below, don't like the white letter look. Might try to do aftermarket ~275-285 tall (EDIT: Lowered that 10 also on Flyn's comments) if I can get the dealer to swap 'em and no serious fender work is needed. I will probably twist the torsion bar enough to get ~1" raise in the front if that helps. Also might see if I can find some tires that have "stiffer" sidewalls that I get the impression the 2500s have which helps in their lateral handling. Thoughts there?)
AN3 - ?Leather Reclining Seats with Driver memory
(So wife and I can both drive without constant seat sliding. Don't care about heated seats personally. Not sure yet if I should go with Natural Color Leather to come close to Light Pewter Color outside or with the Charcoal Leather to match the cladding and interior plastic. Not sure if the Charcoal Leather is hotter when sitting in the sun though. Any thoughts there?)
UC6 - Bose 6-Disc CR Changer Stereo
(Nice to have decent sound without having to do it myself.)
PDH - Driver Convenience Pkg
(Adjustable pedals help with short wife and I like the convenience lights/buttons. Not sure I want OnStar and don't think Front Side Airbags a priority in a vehicle that already does great on impacts.)
V54 - Black Roof Luggage Carrier
(Is this the one you need to add roof carrying accessories like the bike carrier? Figured I'd leave off sunroof to try to keep out some of the Texas Heat. I already have one on my Cavalier and don't use it often.)
BVQ - Tubular Chrome Assist Steps
(I think these look much better than running boards though I might consider getting them aftermarket depending on price difference. Nice to have them included in financed price though.)
Z82 - HD Trailering Equipment
(I DEFINATELY want the 2" trailer reciever and wasn't sure I'd get one at all without this.)
THE EXTRAS
- American Racing Custom Wheels
(From the GM Accessories web page http://www.gmgoodwrench.com/accessories/accessdetailAva_174.html. These look pretty kool. What do ya think?)
- Brush/Grill Guard
(Not sure yet if I want the GM one or an aftermarket. Lots look good, but I'd really like whichever one I choose to be able to handle a light bump if necessary without scratching, flaking paint, or setting off the air bags.)
- Side Window Weather Deflectors
(I hear the tape comes loose so thinking I'd prefer the aftermarket ones that attach inside the weatherstripping. Does your window still close fully and shut out wind noise with those?)
- Molded Hood Protector
(Haven't seen one with AVy logo yet, but probably will get the smoke one without logo.)
- Windshield Graphics
(Dunno if I want this on the front, or maybe would look good on the back window?)
- Black-Out Headlight/Taillight covers.
(I REALLY like the slick look on these aftermarket ones. I saw a pic on this site from someone who had them.)
- Custom Molded Splash Guards
(I like the finished look of these but hear they're not suggested for offroading because they can catch/tear and sometimes do cladding damage when they do. I don't think I'll run into that problem where I'll be, but anyone have any experience with that? What kind of terrain are they prone to snagging on? Maybe will notch them intentionally so they break away easier or something.)
- Pickup Box Extender
(I like the look of these and think they'd work well for keeping groceries near the tailgate while driving/stopping. Also looks like a good place to attach a Bike Fork Clamp for carrying bikes inside the bed.)
- Bed Sport Tent
(Think I'll skip on this and stick with a real tent.)
- Vinyl Floor Mats.
(I like the large size, durability to Mtb Mud/Dirt, and Gold Bowtie logo.)
- Second Row Seat Liner
(Gotta keep the seat nice lookin when hauling house fixit stuff from Lowe's and when the dog is in the back.)
- Hot/Cold Beverage Console
(MAYBE. Sure looks nifty though.)
That's about all I can think of at the moment short of getting into some of the Mods I've seen that help both HP and MPG. Those all look like lots of good fun to me. Can't wait to mod a bit but I'll hold off on drooling over those for now.
Anyways click on search above and put in "max tire size" that will list a thread for you to read regarding what others have done and found.