Here's an excellent firm that has clients across the world.
Egiali Yachting - Home
If you give them a clear imdication of what You want & the style of cruising you want to do they will take good care of You.
Greece is one of my favorites........I would dig into the travel sites & books to see the area of Greece you want to experience (more than a few options).
Even the big charter company websites can give you a peek
Bahamas, Caribbean, Turkey, Greece, Mediterranean Sailing Vacations