We don't recommend couples only resorts for larger wedding groups, unless you think almost everyone attending will be couples. We can get permission to bring a few single guests to the wedding usually, but the guests usually prefer a resort where everyone is not couples.
Jamaica, Cancun or Nassau, Bahamas will have the best flight prices and schedules.
If you are eloping? These resorts are perfect!
For a more unique and off the beaten track destination, consider Antigua, Barbados, Grenada or St Lucia. These 4 islands are close enough to make island hopping a great option also! Get married in Antigua and honeymoon in St Lucia.