Park cities, Preston hollow, etc are just basically the wealthy areas of Dallas, and money certainly doesn't buy one culture, at least not here. Though it certainly is a generalization, for the most part they are just rich people that buy more expensive pick-up trucks and go to wealthier churches.. Most build these god awful palatial houses that they believe are sophisticated because they *think* they look Mediterranean or Country French, when in reality they are farthest thing from it.. I refer to the housing abortions as "Texan Tuscan"
As for fucking Plano, dear God.. It's basically the suburbia that so desperately wants to be Park Cities, but doesn't quite have the money to get there. It's basically flat boring Pleasantville with a huge outdoor mall as the center of entertainment.
Austin really is you best bet in terms of finding a significant amount of more liberal laid back non-religious types, but the traffic is horrendous and no matter what it is still a college town..
Bottom line is Texas is awesome if you just want some place warm to live that has a good standard of living. If your priorities are to maximize income, have a big house at minimal cost, and be able to accomplish errands and daily tasks easily (everything can be had at the strip mall), the Texas is for you.. If "cool" laid back people, cultural activities, diverse ethic people and restaurants, parks, or any type of beautiful surroundings/architecture are important to you-- or should I say more important than the positives I noticed, then stay the fuck away from Texas.
Myself, I moved here because my mother was sick, and have since stayed because I've got a serious Golden Handcuff situation through my job here. As soon as that runs dry or I can't tolerate it anymore, I'll be taking my savings and moving to somewhere in California.