Just a few thoughts from someone w/ 4 kids who has towed with a few different SUV options.
I have no brand preferences, but the '05 Suburban was a huge upgrade from the '02 Durango in most every way. Much smoother, quieter, more comfortable, true 1/2 ton. The dimensions of the Durango might be 'full-size,' but the Suburban felt like a more capable vehicle in every way (save power from the Hemi, I suppose).
Watch out for Denali trim. The 6.0 is a bigger engine, sure, and has a little more power, but comes with full time AWD. You'll be lucky to break 15 mpg with that setup unloaded on the freeway, and despite having the bigger engine, the tow ratings are not higher. A loaded Chevy or non-Denali GMC w/ 5.3 can have all the comforts you'll need, w/o the economy penalty of the awd 6.0 setup.
I would seriously consider the Suburban or Expy EL over the short wheelbase cousins. The rear seat in the Tahoe is a joke IMO. Not comfortable to sit in, and absolutely no space behind it. The Expy for those years is at least a more comfortable seat, but still has no space behind it. Those I know with a short wb are constantly removing the seat, putting it back, etc. The longer wb will provide an actual, usable rear seat w/ a few feet of cargo space behind it. Other than the rear seat, the longer vehicles drive the same, cost the same, get same fuel economy, etc. Unless you really can't have the extra 18" in length, it is a no-brainer for me to go w/ the Suburban/Yukon XL/Expy EL.
The 6 spd is a huge upgrade from the 4 in our '05, well worth an extra bit of change IMO. Our '10 tows much better, drives nicer (the 4 had a huge gap between 2nd & 3rd, making the vehicle feel sluggish and unresponsive at certain speeds), gets about 20% better economy on the freeway than our '05 did. I like our '10 as much as any vehicle we've ever had - quite a pleasure to drive, towing or not.
When shopping used SUVs (at least luxury trim), do your homework and make sure it is set up to tow. When we bought our '10 a couple years ago on the used market, only about 1 in 20 had the gears, the optional cooling equipment, etc. that you'll want. This goes for Ford Expy ELs as well (we shopped both). I don't know if the lower trims have it or not -- we were only looking at trucks w/ leather and all the goodies -- but man, it was hard to find either model equipped to tow more than 5K lbs or so.
Related note -- do your own homework! The salesman will wander around and look at the receiver hitch or the tow/haul button on the shifter and tell you "yep, she has the tow package." Both had significant extra equipment as options that are necessary to reach the optimal tow ratings.
Good luck!
