Tobagos Cays is great, but no wifi.
Our favourites are: Dominica
(Portsmouth), Bequia (Admiralty Bay), the Saintes (Guadeloupe), and Antigua
(English and Falmouth Harbours)
All are great spots with good anchorage and wifi. They all actually use the same wifi provider (Hothothotspot - which can be erratic, but seems to be getting better all the time)
Get Doyle's 2 guides (Windward and Leeward) and read about these places. You'll want to visit all of them.