More thoughts: if at North Island on a Friday, stop by the World Famous I-Bar, just down the street from Base Ops. The T-Line guys will give you a ride. The Aviator Ale is good,... and quite strong.
Want to hit the Northwest? Boeing Field (KBFI) is great. They gave us a van for the night, we stayed downtown. The Seattle Museum of Flight in on the field; there's a good "aviation store" with books, shirts, and other pilot stuff; about 20 minutes away from KBFI, on the west side of Puget Sound is a great restaurant called Salty's. Sits right on the water and has a great view. If just doing a gas-and-go, we'll grab the courtesy car and do lunch there (minus the cocktails).
Also, we did Whidbey Island. We canx'd a scuba trip, but ended up driving to the town about 20 minutes away. It's real small, but had a couple of good bars and restaurants. The VFR leg from Boeing Field to Whidbey is a blast.
Like museums? Spend the night a Midland, Texas, and spend a few hours the next day in the Confederate Air Force Museum.
Ft Worth Alliance: they'll give you a free rental car for the night. The Worthington (a Marriott-branded hotel) gives the gov't rate. Last time I was there, the NY Yankees were staying there. It is walking distance from EVERYTHING, including Flying Saucer (hundreds of beers), Razoo's Cajun, Billy Miner's, and one of those Brazilian Meat Houses where you drop about $40 and crawl away in a food coma. About a dozen other good restaurants that I can't remember the names of.
Ellington: reserve a "VOQ" room early from the FBO, if you're on a budget. A very nice setup, and they've got a bar. Head down to Kemah's boardwalk (about 25 minutes) and grab seafood. There are some good nightclubs on Nasa Road 1, but the FBO girls can point you in the right direction.
NASA gives a public tour at Johnson Space Center (about 15 minutes away), but if you work it early using the "military pilot" angle, you can probably get more "behind the scenes".