Houston is a melting pot, so there is some of the best foods here based on that. The battleship is neat, as is Seawolf park, but it'll be a huge letdown if you've ever seen the Alabama. Most of it is blocked off, so there's only so much to see. There are a ton of museums in the museum district, and the zoo is pretty good. Your wife would probably enjoy the galleria/Katy mills/Willowbrook/woodlands mall. There are a few iFly indoor skydiving around houston. There are a ton of concert venues all over like the arena theater that always have music. The heights area has nice trails to ride bikes on. There is a bat bridge on Waugh Dr just like in Austin. There are some very Hispanic areas of Houston if you'd like some legit Mexican food. The boardwalk in Kemah is neat, and has a several rides to spend the day doing. Galveston outright blows, but I've heard the pleasure pier is fun. There's a small schlitterbahn there next door to the aircraft museum. There are a ton of wineries out towards Wimberley/Fredericksburg area the wife might enjoy. If you want to float a river, I would suggest the Frio in Concan. There are several bars with live music on 6th Street in Austin. You can check out the Capital if that's your thing while you're there as well.
Which airport are you flying into, hobby or bush? Bush is way bigger and on the northeast side of town a few minutes from me. Hobby is in a less desirable side of town near the southside, but better Mexican food. Traffic is going to be the worst it's ever been as they're preparing for the superb owl next year. What days will you be in town?