Be careful if you do go for St Maarten/St Martin (Dutch/French respectively) - the taxes (capital gains etc) are huge on the French side - wheras there isnt a cap gains tax on the Dutch side. The internet structure is good from what I remember - they have good DSL and some cafes with wireless around. Its been a long time since I partied there but it was always good for that part of life
Real estate is pretty well priced compared to most other islands although you obviously are going to pay a lot more for beach stuff - which is mostly condos anyway.