Or Erie, Pa? If so, we have stayed at Lampe C.G. and Marina. It is right on the water and has nice facilities. Sites are decent size, grass and pads are paved - rates reasonable. It is about a 20 minute drive to Presque Isle. Bicycle Trail outside of park goes to museum & library area. Also nice cycling trails at P.I.
Sara's c.g. is right outside the park. If you decide to go there, you want to be in the new section behind the restaurants. It is close to the water park etc. but would be a 2nd choice for us.