The East Texas Herp society is having their monthy meeting at the zoo on Friday night (John Hollister on Trans-Pecos Herping, I believe) and the Bayou City Herp Expo is on the NW side of town on Saturday and Sunday (there is a link on the main ks.com recently updated column).
If you would prefer finding your own herps, Stafford is on the SW side of Houston and you should be able to head SW out of there and find some quiet FM ("farm to market"
roads to roadhunt south of 59. A lot of stuff is moving right now so if you can find a quiet road you ought to see some herps.
My experience down in that part of Houston is to find quiet roads that pass through marshy areas or at least with water in the roadside ditches. You should certainly see a few southern things you can't find in Ohio.
Good luck. I hope you find something (or hook up with Andy who is sure to put you on a good spot!).
-----
Chris Harrison