M.D.
I've only been to Cascade Caverns outside of San Antonio, it's been awhile, but I think they were pretty reasonable. I don't have anything to compare them too. I know my kids liked it, they were elementary school age when we went. We lived in San Antonio and went during the summer and it was so cool in them compared to when we came out of them...
I like outdoors, and try to expose my children to it... they seem to really like it too.
have fun!