Try Lake Whitney. There are wonderful cabins there. About one and half hours from Garland/Richardon.
http://www.lakewhitneylodging.com/?gclid=CJqT2o3dtZQCFQ0M...
http://www.lakewhitneylodging.com/?gclid=CJqT2o3dtZQCFQ0M...
The marina at jupiter cove has a floating cabin.
Read the Texas Parks and Wildlife (July 2008) and they recommended the following.
Top 10 Beaches in Texas
1. Magnolia Beach, South of Port Lavaca.
2. San Jose Island, Aransas
3. Port Aransas Beach
4. Padre Island National Seashore
5. Matagorda Bay Nature Park
6. Matagorda Island Wildlife Management Area
7. Rockport Beach, Aransas County
8. South Padre Island
9. Mustang Island State Park
10. Galveston Island State Park