Is Galveston your only choice? I have never been there so I cannot give an opinion on it.
We love being in the DFW area due to the travel options. My husband is on a plane 2-4 times a week. We do not drive anwhere if it is more than a 2 hour drive. You can get deals to fly. We fly to Miami....(NOT child friendly, you MUST be open minded), Fort Lauderdale, Fort Myers, Fort Walton Beach (Sandestin....this August will be 2nd trip there). Most of these flights are less than 2 hrs and you are on a FL beach.
If you STILL want a TX beach, we fly to Harlingen (sp) via Southwest from Love Field, (have to stop in Houston first) then drive to Padre.
I don't know a lot about West Coast Beaches. My daughter sometimes has modeling gigs in LA and we go to the Santa Monica Pier for fun. Hubby plays golf so we go to Pebble Beach, Carmel.
All in all, we LOVE the FL beaches because we can't get to Hawaii as much as we would prefer!! The flights are not bad and hotels are nice. We love Sandestin in FL. Great beach.
IF you still choose to drive, good luck. We are just not road trip type.