If you like alligators and
Aransas NWR (it's run by the U.S. Fish & Wildlife Service as a National Wildlife Refuge), you should try to visit
Brazos Bend State Park sometime. LOTS of alligators and in close quarters, too -- saw so many right off the trail, and some literally on the hiking trail ahead of us, that I began to wonder if there shouldn't be right of way signage to indicate alligator interstates that were invisibly running across some trails.
Brazos also offers up lots of great shorebirds and songbirds, as well as hawks. Just an all around great, wild park. I haven't checked out the
observatory there, but they do star parties and such so that's another unique feature to keep in mind.