I have an SLT "Premium Plus" (so-called) which, it is my understanding, is essentially as loaded a truck as you can get short of the "Denali-Only" features.
AS indicated above, once you are in a Premium Plus, the list of features different between the two has shrunk considerably.
I believe the biggest hitters were the magnetic ride, the upgraded Denali seating, the digital gauge cluster, a different looking grill, and, maybe a few additional smaller items. At the time I purchased mine, I didn't find myself in an incentive-rich environment, and the cost difference between the premium plus and Denali was more than I was comfortable with versus what "more" I would actually get for the extra money.
And, of course, mine is a 5.3 8-speed versus the 6.2 8-speed.
Personally (and I say this without having any experience with 6.2l, which is probably an obscene rocket, given that the 5.3 is no slouch itself), I am extremely pleased with my truck and like it very much. AS I am one of the folks that uses my truck as a car 95% of the time, and a truck 5% of the time, I felt the 6.2 was overkill for me, but, in the premium plus, I got all of the blinky-blinky-lights and buttons I wanted, and, really don't miss the other stuff. The digital dash would have been cool, to be sure, but knowing myself, I probably would have delightfully played with it for a few months, then set it up a certain way and probably never messed with it again (just my nature).
Not sure if this clarifies anything more, but that's my $0.05.
BTW, glad you are liking your truck.