Conn Creek is a small but nice winery located in St. Helena. The staff was very friendly and knowledgeable about the wine and estate even explaining to us the different regions around Napa, Sonoma, Rutherford, etc.
I really liked the Cabernet Franc and the Cabernet Sauvingon. If you're a big red wine fan, they have a flight tasting of just red wines if you don't want to try their mixed wines.
Tastings are $10 for the regular and $15 for the reserve.