What are you guys into/interests? The U.S. has a large variety to share...also, take into considerations weather and which time of year you want to travel.
How long will the trip be? Plan on doing some driving to various states or just want to pick one location and explore it thoroughly?
The Touristy places I've been to that I'd recommend:
In Caliornia - San Diego or San Fran.
Florida - Miami/Ft. Lauderdale is nice... Or north to Orlando which has Disney!
TN Smokey Mountains - BEAUTIFUL and peaceful. Quite family oriented. Rent a cabin in Gatlinburg!
Missouri - Branson area... kinda like Vegas without Casinos. many shows..but most if it is geared toward the family and Senior citizen fair.
Oh, can't forget my home town - New Orleans, Louisiana. Rich history and architecture, night life has PLENTY to offer (always find a bar or dance club open 24hrs). And we can use the tourist support since Katrina!
It's a shame, but i've probably done more travel outside of the U.S.
Give us a little more info and I'm sure we can better make recommendations for your trip.
Either way...it'll be a nice experience.