I would also recommend Sailing Holidays and would agree with Jason’s comments. The Saronic / Poloponese 2 week trip with Sailing holidays is our favorite Greek flotilla we have done so far. Great mixture of some wind and interesting places to go to. Some busy and popular – Hydra; Spetses; Ermioni and some more remote – Monomvasia is the best place we have been on Greek sailing holiday and very few people go there.
We have used Sunsail many times but not from their current base in the Ionian. We have also sailed with Neilson but also not from their base in the Ionian.