The original question was: which mid-2000 (gas) SUV -- the Suburban or the Excursion? I would not recommend the Excursion. It was a poorly designed SUV by Ford as way to compete in the "hot" (at the time) SUV market.
As just one example, the Excursion is prone to rear-axle induced steering. When the Excursion is driven over an abnormality in the road surface that affects only the left or right-side wheels, the leaf springs allow axle-wrap to occur, but the axle-wrap is not equal from side to side (as it is under acceleration or braking). The weak leaf springs allow the rear axle to momentarily become out of square with the vehicle's centerline. The rear axle then steers the vehicle briefly, and unexpectedly. As a result, the Excursion will suddenly shoot one way or the other in a lane on the road when you hit a pothole, bump, etc. This then leads to you overcorrecting and sometimes leaving you wondering why your Excursion is so difficult to keep in a straight line. See http://www.supermotors.net/clubs/for...le_1/index.php
The above can be verified from other websites, including the following:
Bottomline regarding the poorly designed factory suspension: it's a safety issue, especially when towing a trailer. Do a search for suspension issues and/or discussions on rv.net and the like. (it is, however, possible to modify the rear suspension to help eliminate the rear-axle induced steering)
Also, while many think of the Excursion as a "monster" of a truck, and thus capable of towing "anything," the reality is that it has less payload than a 8.1L Suburban. This is due to the heavy curb weight of the Excursion. For your situation, let's run some numbers for a 6.8L V10 4x4 Excursion: curb wt = 7190lbs; GVW = 8900lbs; payload = 1710lbs (8900-7190); tongue wt for a 8000lb trailer at 13% = 1040lbs; new calculated payload = 670lbs (1710 -1040); gasoline wt for a 44gal tank = 273lbs; new calculated payload = 397 (670-273). Without going into further calculations, it should be obvious that adding a couple of passengers and some gear will put you over the "monster" payload (note: the above, calculated payload is most likely less b/c the curb wt of an Excursion, with options installed, is greater than 7190lbs). The heavy Excursion also has a lower towing limit (11,000) vs the 8.1 Suburban (12,000).
For mountain towing, the Excursion also takes a back-seat to the 8.1L Suburban. The Excursion produces a max of 425 pound-feet of torque at 3,250 rpm; the 8.1L Suburban produces 445 pound-feet of torque at 3,200 rpm.
If you do some research, I think you'll find that the Excursion, despite the image/advertising by Ford, was never ready for prime-time as a daily driver or as a tow vehicle (note: despite the poor handling capabilities, many soccer moms found the Excursion desirable from an accident or fender-bender perspective and a passenger/cargo capacity). Hence the reason you'll find many Excursions for sale but not too many 8.1L Suburbans.