Hi Forrest,
If you're near Peninsula State Park, the
Sunset Trail is a leisurely ride with some great views and nice stretches through the forest. The paved roads through the park are also really nice to ride on and car traffic was low in my experience. (I camped in the park Sun - Wed this past October, so I can't speak to weekend or summer traffic, but I imagine it's a bit busier.)
I'm hoping to get back out that way this fall to explore more of the area by bicycle. There seemed to be plenty of smaller roads off the main highway on the bay side that would connect you to other parks and small towns. Hopefully someone with more experience in the area will chime in with some routes.
-Danny