Pinballz in Austin, TX has a phenomenal selection of DMDs (somewhere around 120 +/-) all kept in great condition by roving techs. Also a few EMs, SSs, and vids.
Open 7 days a week. In general, no wait to play (coin-in).
Owner welcomes emails on specific games you want to play on your trip to ensure they're working.
http://www.pinballzarcade.com/
PBHOF is also open 7 days a week; has great mix of DMDs and a large/fantastic line-up of EMs with a nice row of vids too. Over 200 games. Also coin-in.
Joystix in Houston is also a really nice place; but unfortunately, it's only open to the public two Friday nights a month from 9 pm till 2 am. Games are on free play for a $20 admission fee.
Also looking forward to visiting some of the other venues mentioned...including a pilgrimage to LTG's SS Billiards!