I 2nd the Petit Jean SP idea, awesome place. If that doesn't appeal, check out the Buffalo River NRA in Arkansas. We stayed at Shady Oaks near Jasper when we visited the Buffalo River area.
In Missouri, there is the Ozark Scenic Riverways (lots of canoeing there), and another beautiful area is the Arcadia Valley (SW of St. Louis). Beautiful State Parks in the Arcadia Valley include Johnson Shut-Ins and Elephant Rocks. A real nice private CG in that area is Big Creek RV which you could use as a hub.
Other places in Arkansas to consider are Mt. Magazine SP, & Lake Catherine SP. Enjoy!!
