Being from San Antonio, and having friends and or family in all of the places that have been mentioned, I would say, stay a month each in Rockport, Port Aransas, and San Antonio, then maybe somewhere in the Valley ( South Padre, Brownsville, etc., ). They are all multicultural, and you will have much the same situation that you have in any state, city vs. small town. San
Antonio will have more restaurants, shopping, etc. The others have a much smaller town atmosphere, but you are on the coast for the most part. Rockport is on the bay, while Port A is on the Gulf. As far as qualifying one area over the other as being more high end than the other, I think that is difficult to do. George Strait and Fully Clingman(retired CEO of HEB, one of Texas' most successful corporations and best grocery chain) own vacation homes in Rockport, as well as many other very successful folks. Port Aransas and South Padre are similar, with lovely homes in different areas, from the beach to housing developments and they are all over the lot. There are nice golf courses in both Port Aransas and Rockport, PA is public and Rockport is a private club. Both have good restaurants, however my experience has been that Port A does better in the high end restaurants. Rockport has a better grocery store, but you are maybe 25 minutes from a good store when in Port. A. The point being, it just depends on what you want, hence the advice to give each a try. I would say, if weather is is the most important thing on your list, the Rio Grande Valley is your best bet. Rockport seems to have more RV parks, definitely more resort parks. Port Aransas has Gulf Waters, which is a lovely park. We have 2 different friends who own lots there, and we have stayed there several times. It is pricier than some parks, but very nice and there is a sense of community there, but I am sure that exists in any number of parks. I think you just have to take some time to investigate. Good Luck with your decision and in any case, here's an early welcome to Texas, hope you have a great time, wherever you land!
Safe Travels,
Susan