Nice truck, John. An SLT with nice seats and power goodies. It looks like it has been well cared for. Mine is the base ST- crank windows, manual locks and the clunky plastic door panels. Easy to clean, though- It's a work truck 
Your fuel mileage average should get a bit better once you mix in some highway driving. A buddy of mine has an '04 1500 quad cab with the 4.7/auto and gets around 12-13 with mostly local driving.
Believe it or not, my big diesel gives me 15-16 driving mostly local, and about 21 on a highway trip. I use the 6th gear (overdrive) as much as I can. The 2500s with the big Hemi gas V8 are GUZZLERS, I can understand why they sell a lot more 2500s with the diesel. ~Jim