I lived in Austin for two years, 2004-2006, while going to grad school at UT, and I've visited San Marcos and Fredericksburg a few times. (I don't know anything about Wimberly.)

I cetainly liked Austin proper, and if I were to return to Texas, I would live in Austin itself, and definitely NOT in one of the Northern suburbs like Round Rock, Georgetown, or Cedar Park. They have a reputation for being somewhat conservative and "stuffy."

Fredericksburg is a very quaint town, somewhat picturesque but also somewhat rural and thus lacking both the conveniences and amenities of a bigger city. (For example, there is no Barnes & Noble, Best Buy, "artsy" movie theater, etc.) For that you would have to drive 2-2.5 hours to Austin.

San Marcos, on the other hand, is larger than Fredericksburg and is full of chain stores and chain restaurants, and not at all pleasant like Fredericksburg. I would avoid it if possible.

As for the tolerance factor, I really don't know what it's like outside of Ausitn, but in Austin I felt quite comfortable.

Good luck in your search!