Dave,
It sounds as if you are taking a well planned and cautious approach to boating. You will hear a lot of doom and gloom stories about the Delta and Bay, but both are doable as your experience grows. Hone your boat handling skills on the lakes and when you feel ready start working on the Delta. Try to launch and retrieve during slack tides and pay attention to the weather forecast. The main differences between the Delta and lakes are tide levels, tidal and river currents and the vast expanse of water that is easy to become lost on.
Your boat is a little small for the Bay, but if you pick your days carefully and stick to sheltered waters, you can do some exploring on the Bay. The Alameda/Oakland Estuary is a great place to poke around. You can also launch in Sausalito and explore Richardson Bay; on a good day, you can cross over to Angel Island, but really watch the winds. They usually pick up in the afternoon and can make the return crossing rough. I assume that your boat has an open bow which presents your greatest danger when the water gets sloppy. If you stuff the bow into a wave, you can get a LOT of water into the boat very quickly.
Build your skills and work your way up gradually. BTW, you could spend years exploring in the Delta and still not have seen it all. The Bay can be fun, but actually has less boating attractions or destinations. In the Delta, you can jump from one restaurant/watering hole to another all day long. If I can offer you any advice or suggestions, please feel free to email me.