If you are headed to San Antonio, you might end up going to Ripley's Believe It or Not. This is a great place to visit and is right across the street from The Alamo. It can get a little expensive though. When we went recently, we figured out that the best way to do it is to buy the combo ticket.
You can't get this ticket online but can get it in person. Instead of just going to one museum or attraction you will get to go to five of them. It does cost more of course but it is the only way that you can afford to go to several of the attractions. We figured out that it was cheaper than paying for 3 of them on their own and you get to attend 5 in the combo package.
We got to visit the 4D movie, Ripley's Haunted Adventure, Wax Museum, Ripley's Odditorium, and even the Guinness Book of World Record's Museum. Our favorite thing was the 4D movie. It even sprayed you with water and had snow falling from the sky! The World Record Museum had an area upstairs where you could try to beat a record and that was a lot of fun.
If you are going to go to Ripley's Believe It or Not in San Antonio, I would highly recommend the combo package to save money! It kept us busy for about five hours and the kids had a blast.