gk gets it.
I love Nashville. I really like L.A. (Venice/Santa Monica are tops for me, but I also like places like Pasadena, downtown, and some of the southern LA/OC beaches). Dallas is great and so is Houston. In fact, Texas/OU weekend and St. Patrick's Day weekend in Dallas are phenomenal weekends on their own. Chicago is great. Louisville is actually a great city as well. It's still a Southern city in most respects, but tons of Catholics there, so bars, drinking, and festiveness is aplenty. Tahoe is great. Denver is pretty cool. D.C./Alexandria are great for history and single life in your 20's. I've had great times in Atlanta, but it's not high on my list of places to visit.
A couple places that I was only "meh" on were San Francisco and Charleston. They just didn't do much for me. I actually did like Menlo Park/Palo Alto south of San Fran better than San Fran itself.
Of course the quality of visit and enjoyment had are influenced by so many factors (work, wedding, friends, budget, etc), I think it's sometimes hard for us to give truly objective feedback.
Some honorable mention locations from me: Bucksnort, TN, Needmore, AR, Blue Ball, AR, Big Bone Lick, KY