My sister, husband and family rented a cabin for a week right along the Southern side of the Muskegon Channel on Fulton Street. It's a beautiful walk to Pere Marquette Beach for sunsets, and you're also near the beach on Muskegon Lake. The cabin was beautiful and was built right into the sand dune. I'll have to see if I can find it online.
Here is a link right to the spot on googlemaps:
http://maps.google.com/maps?f=q&hl=e...wloc=addr&om=1
It's also cool to watch the boats and the ferries coming and going, and they were there during the Tall Ships Festival and watched the scooners (sp?) coming and going.
Hoffmaster (as mentioned) is a beautiful state park. The downside it is quite a hike through the dunes to get to the beach from the campground, unless you drive over to the public beach.