Hi,
San Antonio bay is not a pleasure boat area, mostly commercial stuff.
Am I correct that you will be in the San Marcus area? ( I did read the threads..lol, ) The best saltwater for boating and fishing is Corpus Christi. For beach going, padre island is the place. word to the wise, Texas is very warm in the summer, some say down right hot as hell.
For night life, go to Austin's 6th street, party central on weekends. Great music!
Big change from the Atlantic. Best of Luck
Smitty