First time overnight, you can’t go wrong with Avalon. It is the most protected in anything but Santa Anas, and you can get dinner there and walk around. We tend to favor Avalon in the winter (no crowds) and the Isthmus in the summer.
It is a long way around to Cat Harbor and it is a ghost town in the winter. If you stay in Isthmus Harbor, just ask the harbor guys for a protected spot when you
radio them for a mooring assignment. There is lots of room in the winter and they will likely give you a tucked in spot on the west part of the mooring field. The wind can blow through the low spot of the Isthmus like a bit of a wind tunnel but usually not really a problem. You can easily get a more sheltered spot by asking and be out of that wind.
Cherry Cove and 4th of July cove are sheltered but farther away from the pier etc and can feel a little
remote in the off season. Depends on what you llke but it is hard to go too far wrong.