Not sure if this reply is too late, but here are my two cents:
I grew up in Corpus Christi, and I lived in Houston from 1994-1999 and lived in Dallas off and on for a total of 3 years between 1988 and 2000.
When I left Houston for good in October 1999, it was in the middle of a mosquito plague (ok, it felt like a plague). You know those cliches of Americans driving to pick up their mail from communal postboxes? Well, our postbox was on the way home, so we did happen to drive to collect it, and during one of those days of the plague, I got bitten by 8 mosquitoes during the 10 seconds it took me to get out of the car, collect the mail, and get back in. Awful!
On the other hand, I made a business trip from Houston to Dallas in the summer of 1998 and thought I was going to burst into flames from the oppressive heat in Dallas during the short walk from my office to the car park. This, having already been acclimated to the climate in Houston!
Aside from the weather, Houston seemed to me to have a better proportion of independently owned restaurants with better quality, more imaginatively cooked food than the average variety chain place. If anyone has ever been to Ruggles, you'll know what I mean! Of course, Dallas has some decent restaurants too, but on balance, I felt that Houston had better ones.
Having said all that, if I were forced to choose between the two, I would choose to live in Dallas.
Let us know how things turn out for you!