Re: Dallas area
I thought the Texas School Book Depository had a pretty decent walking tour. IIRC, the last time I was in Dallas, it cost less than $ 10 for admission and that included a cassette tape that would guide you around the building (WARNING: bring your own headphones unless you have no problem with community earwax).
"Booing on opening day is like telling grandma her house smells like old lady."--WOY