When I was out that way I regret not stopping at McDonald Observatory.
http://mcdonaldobservatory.org/

The ferry across the Mobile Bay at Dauphin Island is kinda fun.

In the Florida panhandle there are some spring-fed streams that manatee occasionally wander up, although probably not the time of year your hubby will be there. Canoe rentals/shuttles are pretty easy to find. I canoed down there in February and it was a neat time even though the leaves were off the trees and it was kinda cold.