I bought my Avalanche in 2006 and have had it until present. I have put quite of bit of miles on it, and seems to be doing just fine. The transmission did go out at 116k miles because of the four wheel sticking in between 2wd an 4wd. All in all this is a really good driving truck, makes parking lots a breeze to pull into, and can handle when you press the gas pedal through the floor as well. You can't go wrong with it if your wanting a SUV and Truck together.
The steering wheel audio controls are the best, dual climate control, turning radius, and how the back glass comes out along with mid-gate folding down. The back glass is easily stored onto the mid-gate. The sound system is great as well because of the Bose.
The push button 4 wheel drive should have been designed better along with motor that controls the engaging, better fuel economy, should have out the 5.7 L instead of the 5.3 L, and GM should have used the 4L80E trans instead of the 4l60E to pull its mass.