I love Pigeon Creek, and Riley Trails. Pigeon creek is really nice, it is also where we cross country ski in the winter, it has a lodge, maps and bathrooms. Even lighted trails. Riley Trails is in Holland and is a bit more rustic, but the trails are easy to follow.
We love Hager Park in Jenison, it is a great set up for all ages, Molly could even crawl on some of the equipment last year, when she was just learning to crawl. You can also walk on the grass map of the United States. It has a bathroom and a working drinking fountain too!
Another great option is Timber Town in Zeeland, it is a lot like Hager but also has a pond with ducks and a skateboard area.
We defiantly have a lot of great beached in West Michigan, but my favorite for families is Tunnel Park in Holland. It has a free place to park, bathrooms, playground equipment, a tunnel leading to the beach, and a giant dune to run down! So much fun!