To each his own, I guess. FW, Austin, San Antonio and Houston. I've been to them all, but never on the same trip. I think I would try I-49 for a more direct route, unless you wanted to visit those cities. Maybe someone else could chime in on that.
Once on I-10, there's the Battleship in Mobile. Yes, the Blackwater SP is nice and its pretty close to the beaches. There is also Florida Caverns SP. If your looking for scenery, I-75 is not the best place to see any. I would suggest getting off I-10 east of Tallahassee and go down US-19, if you were going to Manatee Springs. Then you could cut over to Alt-27 to 75 and TP to Walyworld.