If I'm in traveling the United States, my favorite place is the Texas Hill Country which runs west of Austin. There are dozens of spring fed white water rivers, mountains to climb and hike, just about any outdoor activity you can think of. You can really get away from it all and enjoy nature.
Outside of the US, my favorite destinations are Southern France and Southern Italy. The culture, the food, the wine, the mountains and cliffs overlooking the miditerranean, and the history (especially Rome, Pompey... are amazing.