JTK--you'll love that engine / tranny combo! I had the same truck (2015 Quad Express 4X4) until December 2017 at which time I traded for my current Hemi-powered 2017 Crew Cab Big Horn. I wasn't looking for a new truck in December but found myself at the dealer for a state inspection--while waiting I started talking to a sales rep and told him to quote me a 2017 Big Horn with the same 3.6L / 8-speed tranny combo. Sadly, all they have on the lot are Hemi's and that's what they were having a blow-out sale on. Honestly, I didn't think the numbers would ever come close to working, but they discounted the 2017 heavily, and gave me way more for trade-in on the 2015 than I would have ever dreamed. The trade up was equal roughly to the cost of the higher trim-line.
I loved the Express, but I wanted more options like back-up cam, nav, crew-cab, heated seats etc. I would have preferred the 3.6L engine on the 2017, but the Hemi is nice to have and lower gas mileage doesn't really bother much as I don't put a lot of miles on.
As for the extended warranty. . . I don't bother with them--I'd rather bank the money for maintenance and roll the dice that nothing major happens.
Have fun with the new truck!