We camped overnight in a tent at Manatee Springs in #80. Be sure to bring tick repellant; this park is lousy with them.
The park is nice, small, and well-maintained. I wasn't thrilled with the bathroom on our loop, as only one of the showers had a stall door, and the door to the building opened very easily and would stay open unless the person who left closed it behind them.
We paddled on the river, walked the boardwalk, saw a ton of gators, and had a nice weekend, but I don't think it's worth a return visit. Not that it's a bad park, there are just a lot of parks with more to offer within an hour or two of Manatee Springs.
Generally, we prefer dispersed camping because campgrounds can get pretty loud. This was absolutely the case when we stayed the night, as some of the people on our loop (college guys) were up late drinking, shouting, and playing loud music.