Desi, something else to look at during your visit, city pass. When I have hosted tourists to the area, I normally suggest they use this (I've even used it during my times staying at my Houston home as a "local"). You pay a flat fee and get access to NASA, and many of the museums and local attractions.
http://www.citypass.com/houston?mv_s...FUPr7Qod6QLEIQ
I suggest this as a great way to see many of the sights for a good price.
Ciao,
FH