We were in Piedmont two years ago. The Langhe wine area is not well served by public transportation. We rented a car and drove through the region, stopping at the towns of Cherasco, Barbaresco, Barolo, Neive. It was terrific, but not what you asked for. I suggest taking the train to Bra, home of Slow Food and a nice medium sized city. Then check out the wine and food tours from italianna.com which start from there. The owner is a transplanted Californian. I follow her blog, and the tours look great, I haven't taken one personally but the online reviews are solid.
You will love the region and the wine. If you do end up driving, the roads are well maintained and well marked, but watch the speed limit. There are very innocuous looking grey metal boxes on the sides of the roads. About the size of a mailbox, but they contain speed cameras. Why would you rush, though? It's so beautiful. Have a great trip.