GMC Forum : “Denali 08 - 07... any good? or Tahoe LTZ 07-08 ? in terms of luxury,Gas consumpt...”

Did you happen to notice how much they have in common?  Down to the same factory they came out of.  The biggest difference will be in the luxury dept.  And that's only because what the LTZ package on a Tahoe is, is a bunch of options added in.  The same to say how the Denali package is on the Yukon.  So you are just comparing options packages.  Gas consumption will only vary in that the more options the heavier your vehicle.  But it's not enough to be concerned with when the vehicle is pushing 4000 pounds.  Utility and functionality are both awesome.  And durability plays more in maintanence now days then actual build quality.  I hope that helps.