I will "assume" since you have a bunkhouse, that you have kids, so let me tell you about a great MD SP....Point Lookout SP.
They have a wonderful nature center with programs all weekend for kids. It is on the spit of land below Annapolis that is where the Potomac runs into the Chesapeake.
It has lots of history, started as a resort, then a hospital during the Civil War and a POW camp. There is a large fishing pier, a great little lake to paddle around on with canoes or kayaks, a beach area, and a light house.
We camphost there for the month of June and it is wonderful, if slightly buggy.