Leelanau County, Michigan.

If you're looking to head somewhere as the warm weather winds down, try Michigan's Pinky -- the Leelanau Peninsula. Beaches, vineyards, lots of little lakes, one Big Lake, and plenty of great towns. 

Though, now that we think about it, it's even nice in the cold weather with some skiing nearby, plenty of hills for sledding, and more room on the beaches in December!