I'd suggest you check out the Vallejo Yacht Club. The VYC has a reputation for the most friendly members. The harbor is one of the least expensive in the entire bay area. There is an active club racing program. The club also hosts the YRA season opening race to over 300 boats (including the biggest party in the bay area), and the Vallejo 1-2 race in October. The club is the closest to the Napa valley, and it's close to the delta AND the bay. AND it's warmer than the bay but cooler than the delta. There is a great club house with a family atmosphere. Stop by and check it out before you make a decision--you'll be glad you did.
San Francisco Bay