Bastrop is probably a good choice for tenting in the summer as the trees will provide a good deal of shade. The only real "issue" with this park has to do with the road noise coming from Hwy 71.
I don't agree with the generalization about the Texas coast. Padre Island National Seashore is a crown jewel which goes virtually unnoticed by many. Check out
this link. The pics represent a small glimpse of our experience there and all I can say is, I wanna go back! We had literally miles of beach to ourselves.
Haven't been to the other parks mentioned here, so I can't comment either way.