If the Denali price is correct...GM has a good buy...BUT....I just priced out a (edit-Nicely Loaded) 07 LTZ at $50,070....and the 07 Yukon on Ebay, add all other options (Nav,DVD,etc) .....and you are over $50,000.............
So, I am betting a Loaded 07 Denali goes for $53,000 ++++, the base price is bait or lets see when the stickers are on the window...
Edit - I also priced out a 07 Yukon 4WD SLT (Fully optioned) @ $53,120 w/20"......the LTZ is the same price fully optioned...Yukon or Tahoe, same price
As far as materials or quality Tahoe vs Yukon, options are the same price, I would say other than some sheet metal, same thing.