I fish the bay a lot between the Annapolis area down to the Solomon's Island area. The best top water action for Rockfish is during early Fall when the fish begin to school up in big numbers. Most times you'll have to burn a bit of gas to run around and find birds, but when you do, often times you'll have non-stop action for a while.
I've heard that there have been smaller pockets of Rockfish schooling in the Thomas Point area outside of South River recently; mostly in the very early morning at first light. You may even find bluefish mixed in. In my experience, there is no magic spot. You'll have to experiment with fishing different tides/conditions in different areas. If you are looking exclusively for top water action in the bay proper, you'll have to get out early and cover a lot of ground until you find fish.
--