Monbazillac isn't a grape but a place. The wine is made from Sémillon, Sauvignon and Muscadelle grapes. It's a good dessert wine.

Petite Syrah is an interesting lesser-known grape, pioneered by Stag's Leap in Napa, now being made by Ridge and others. And if you're in Napa, try Heitz's wine made from the Grignolino grape, otherwise almost unknown outside Italy. Heitz do a very interesting wine which tastes quite different from anything you'll have had before. They also do an excellent Grignolino port.