A couple of options
McKinley Marina in Milwaukee is great (newly refurbished floating docks, and facilities). In addition, both Port Washington and Racine are nice day sails from Milwaukee The only downside to McKinley is they charge you an arm and a leg for trailer storage ($15/day). Concerning inland lakes, Mendota in Madison is supposedly pretty good and Madison is a pretty cool place to hang out. If you want to consider a little longer trip, Door County is great. Lot's of boats hang out just off of Peninsula park and there is lots to do. You can park your car in Peninsula Park State Park for a couple bucks a day. They do have showers at the campground but there are also plenty of marina's as well. If you do Door County, get a good set of charts, and then talk to some people at the marina's because lake levels are still low. Good luck and have fun. I'm envious!
