Re: South Haven
What kind of boat and what type of activities are you planning to do?
I'm not sure how far from South Haven you are looking for...however, Gun Lake is about 1hr to the East. It is a nice lake...pretty shallow but for watersports it is nice. I'm not real familiar with any other lakes that would be closer to South Haven.
Also, the Saugatuck waterfront is a must see. You could run up the shore to the Kalamazoo River Inlet from South Haven to get to Saugatuck...of course that will require relatively calm winds in a smaller boat.