K.A.
I have only been to Miami and Key West in Florida, and the beaches were really nice. If you want to go to a Texas beach, Galveston is not the most attractive option. If you dig down very far into the sand, it is black with oil/tar. There are a lot of other things to do, but it sounds like your son just wants to play on the beach. We go to Port Aransas every year, and it is very good for beach combing. It is hard to find a beach front place in Port A because of the dunes. We usually stay at the Courtyard. They have kitchens and are reasonably priced. They have a pool and are walking distance from the beach. There is a beach closer to Corpus Christi called Malachite Beach. The sand there is really pretty. You go there for the day, but you have to camp if you want to stay overnight. The prettiest beaches in Texas are in Padre Island. There are no dunes there, so many of the hotels have beach access. We went for Thanksgiving three years ago, stayed in a lovely condo and had a great time. Good luck!