I can't offer personal advice, sorry (this is a British-based site but there are some regular American posters who may be able to help). But for this sort of thing you could always try to contact the local convention and visitors bureau - advising visitors on local attractions is part of their job. Here's Dallas's:
http://www.visitdallas.com/visitors/
And this is Houston:
http://www.visithoustontexas.com/
Phone them up for more advice if you don't see what you want online - that's what they're there for. Have a great time!