I'm with the others, the 4.30 gears will make your pulling experience more favorable. Empty around town should be about the same mileage. Empty on the highway will get slightly worse mileage with the 4.30 gears. Towing, that lower rear end will give you more grunt from a stop and have you cruising at lower RPM's.
You have some hills in the eastern part of your state, so if you go over there you will be very happy to have the shorter gears. Then again if you tow to the beaches or south and don't plan to encounter those hills, the 3.73 gears will be fine.