We have 22's on our Denali and they seem to be a good size to go with. However, for looks, I dropped the back by 2" (eibach springs) and dropped the front just a tad via the torsion bars to help close the gap between the tires and wheel wells, strictly for looks though. Didn't jepardize the ride (in my opinion). I have been told by a couple others who have put the denali lowering kit on it- 3" in the front and 4" in the back, absolutely killed the ride and wish they hadn't put it on. Also, I think 24"s look better than 22"s if done right. I do like the wheel that is pictured above, a nice wide lip with a clean (not too busy) straight spoke.
As for Rubber- I am a real big fan of the new Toyo Proxes II tires. I previously had The Toyo Proxes I, size 305/45/22's and got 55,000 miles out of them (religiously rotated them), they were great tires. Now I have the Toyo Poxes II's, size 305/40/22's (so lower profile than my proxes I's) and they ride just as smooth and quieter than the Proxes I's, and seem to do better in rain/wet conditions.
For what it's worth, we run 20" bridgestone re050 potenza's on my wife's CTS and have had to replace 2 of them in less than a year.
I like the Toyo's, they are reasonably priced too. In my experiences, the bridgestone's are ridiculously over-priced for what they are...