I have an '02 Denali XL (100,000 miles) and here is the list of things I have fixed. Hopefully this is helpful to other folks:

1. Headlights and Sockets (warranty kept burning out)
2. Intermediate shaft (warranty fix,steering wheel knock, replaced at 60,000. Problem came back at 90,000. just and annoyance.
3. Front Diff bearing (preventative maintenance)
4. Driver side mirror (cracked during a 115 degree heat wave)
5. Emergency brake cable and pad (dealer)
6. Windshield wiper reservoir and pump (was leaking and its an all in one system)(fixed at speedy lube)
7. Front end suspension squeak (fixed myself with tri-flow)
8. Passenger side door panel squeak (fixed myself by wedging in cardboard)
9. Rough idle (fixed myself by buying superchips tuner, love that thing!)

Things still need to fix: (probably too much $$)
1. interior dash and steering wheel lights are starting to burn out
2. Ventilation system making small clicking noises in dash (sounds like failing servos on blend doors)
3. Transmission undulates a small amount when accelerating from a stop
4. Brake pedal vibrates badly when hitting a sizeable bump/pothole in the road
5. Slight squeak noticed from where air intake meets motor

Overall has been a great truck, hard to live without it after owning one!!! Tell you what though I could never justify buying another one new. Depreciated $40K in 5 yrs. I cant wait to buy and '08 in a couple of years.

Just fixed a couple more things:

New radiator put in.
Radiator had a crack in it- If you turn off your car and hear a hissing sound or circulation sound, thats a good indication. $580 installed.

Third intermediate shaft put in. What a difference, no more knocking in the steering wheel. $195 installed.