Realize this is an old thread but I would imagine that others will check it so a couple of thoughts.
1. The outer anchorage in English Harbour can get quite nasty will the wrong swells.Plus it tends to get quite crowded so there is not much room if you (or your neighbour) starts to drag). In these conditions you can go into one of the little bays to the north of the Dockyard and anchor in mud. These spots are incredibly protected from wind and swell to the extent that we could not believe it was the same day. These bays can be buggy though when there is no breeze at all.
2. I agree about Nonsuch Bay. It is a lovely spot to spend a few days.
Finished the circumnavigation in early February in Grenada. Have to work on a book project for the next several months so the boat will be waiting for next year.