If you're under 21, I would just call around. I used to get motel rooms before I was 21, but that was back in the day. I was driving down the Seawall at lunch and noticed a few- the Commodore looks like it might work. Just do a Google Search for Galveston Hotels Seawall. Call the ones on the seawall that aren't big chains. Also, when you're checking in, just one person go to the checkin, without your boys sitting in their cars out front.
Before I was 21 I stayed at the Key Largo. They let us in even though we weren't 21, but we did have the hotel detective come to our room once.
aite im about to make reservations at treasure isle...is there any motel better for an after party??? and thanks for all the help