My top tip would be to get the show on the road fairly early during the busy season. Mooring balls - at least the nicely sheltered ones - fill up early at some anchorages. Early in the afternoon (ie 2 or so) is a good target for the smaller anchorages. Cooper island is probably even earlier than that.

Also, IMHO you should visit the baths by renting a car at Leverick, swimming in and leaving the boat is not worth the hassle. There's whole recent threads about that one!