Some suggestions
I'd either start in Martinque or St. Lucia, depending on cost and ease of travel. Head north as far as Dominica stopping at Martinique (If starting in St. Lucia), les isles de saintes and Guadeloupe. Then providing the charter company allows you to sail at night, id head straight for Grenada then work my way back stopping at Carriacou and through the Grenadines. A 10 day/ 20 day split would allow plenty of time.
Alternatively the islands around Greece are also very nice and it would be easy to put together a R/T itinerary.
You could also consider the South Pacific, based out of say Tahiti and explore the surrounding area. Travel costs will might be a concern though. I haven't sailed in the South Pacific yet, leaving this Saturday for a 7 month charter, but it looks beautiful

Drink all day at home, your friends worry about you; do it on vacation and they say "what a good time you're having". Save your friends needless worry, travel more!