There are many local tour operators that will shepherd groups from winery to winery, including winewagentours.com (a VW Bus!) and grapevinecountrytours.com. Be sure to check each winery's site for seasonal hours before visiting.
Mike and I did a wine tour together and visited Goosewatch, Sheldrake Point, Buttonwood Grove, and Americana Wineries!
One of our favorite guilty pleasures - delicious, homemade ice cream! Mike and I frequent here when driving back to Brooklyn from Geneva.