I just picked up a 2010 Avalanche with 36,000mi on it. It replaced my 80-series as our family camper for several reasons: more seat space, I need a pickup sometimes, lockable bed sides, shorter wheelbase than any other full-size crew cab, 6-speed transmission. Mine has one option, the tow package so I have a transmission cooler and 3.42 gears with a G80. I replaced the front struts with 2" lift struts and upper control arms. This leveled out the truck for now and it fit 285/70r17 tires on the stock wheels. This weekend I finished the bed rack so we can mount our RTT. I'll have to see how much this weight affects the rear suspension, but I carried an engine back there and it didn't squat. A 57' Chevy on the full Uhaul car trailer did squat it though.
Future plans will be new wheels and tires (275/70r18) and maybe a small body lift. Maybe do bumpers and sliders but I don't want to add a ton of weight.