Since Windsurf goes into those small ports that are not frequented by other cruise lines, we're having some problems getting info on the following ports. We like to do independent sightseeing in ports and are adding this to our Europe ground trip on pretty short notice, so any info would be much appreciated. Please feel free to e-mail me at email@example.com.
Mahon, Spain (Minorca)
Marseille, France (I think we've got this one under control because we've done it before, but I'm always interested in other tips and opinions.)
Isle of Porquerolles
St. Florent, Corsica
Afraid I have no firsthand knowledge of most the ports that you mention but did visit Mahon in May aboard the Seabourne Legend. This is a delightful port and you dock right in the centre of town (not that the town is that big) lots of nice shops and cafes to wander around without need to revert to taxis. For the more energetic and adventurous there is a cycle hire shop right by where the passenger boats dock and they also hire out motorised scooters.
One of the prettiest ports in the Mediterannean to sail into so make sure you are on deck early as you enter the harbour.