At least until the traffic to the restaurant calms down about 10. It is busy early in the morning too. As usual there are a couple of lobster boats that seem to enjoy roaring past visiting yachts at 5 AM. Most are considerate though. The best mornings there are on days when the low tide is negative around dawn so the lobster boats don't head out through the gut between Little and Great Cranberry islands. It is certainly a scenic spot to have a leisurely dinner and watch the sunset.
As far as sailing the Great Harbor goes, I agree it is usually pretty nice. Most of the time there is more wind in the harbor than outside the islands, particularly on sunny afternoons when the sea breeze kicks in.