Used to enjoy going to Fiesta Texas during the offseason.  No lines and the workers were so damn stoned you could basically do anything.  Had a season pass for awhile and was always getting cheap/free tickets.  Got to be that you'd recognize the performers and go, "this is the third year in a row I've seen that blond sing boogie woogie santa claus for minimum wage..."  Anyway, nice diversion for 2 or 3 hours and it was only about a 20 minute drive.
Sea World, though, meh.  The last time I went, I got to listen to how killer whales have a range in nature of thousands of miles while I watched one swim around in circles in a tiny swimming pool.  That was it for me.  Blackfish is a great documentary if you like listening to crazy, attractive people talk.
Houston.. well... AstroWorld is now a parking lot for the Houston rodeo.  And we've got some scammer that's been raising money for "Dinosaur Land" for at least 20 years. 

EDIT: The dinosaur scam is still going....  
http://www.earthquestadventures.com/