We've stayed in Pancake Bay and LSPP in the past. Both are great stops, but we find them more suitable for smaller RV's, we bypass both of them these days with our 36 ft. 5er. Anything over about 30 ft. will make it "fun" to shoehorn into sites and your RV will be scratched up by tree branches on some of the corners (specifically in Rabbit Blanket campground in LSPP).The hiking and the petroglyphs (sp?) in LSPP are great.
That area is devoid of shopping with the exception of a store within walking distance just south of Pancake Bay PP that sells local crafts and souvenirs, Wawa is north of LSPP and offers basic shopping. Otherwise, it's the "boonies"