I always suggest
Green Caye RV Park in Dickinson, TX. It is about 15-20 miles from Galveston, 30 minutes from downtown Houston, 15 minutes from the Kemah Boardwalk and easy access to shopping and other things in the area.
There are others in the area as well. If you see one your are interested in, PM me and I'll give you my "take" on it.
Let me know what you decide and I'll give you "easy" directions.