We spent a few days last week at Bay Harbor Motorcoach Resort just south of Petoskey. This was our second stay there and we really like the resort. It's smaller (78 sites), beautifully landscaped with a great clubhouse, pool, tennis court, and even mini-golf. Petoskey is about 5 miles in one direction, and Charlevoix is about 5 miles in the other direction. It was only about 1/3 full last week during the week, and they had a special "pre-season" rate of $49/night. It is a Class A, 2000 & newer-only resort.
Hearthside Grove RV Resort is just on the north edge of Petoskey and gets rave reviews. It is, however, much larger, and we usually like smaller resorts. We might give this one a try next year, however.