A lot will depend on the ship as well. Here is what I know about the following ships to the caribbean in March:
Zenith has NO balconies.
Horizon: has ONLY one balcony........and I would guess that at this late date, it's probably booked.
Century does the Eastern Caribbean every other week (alternates with Western Caribbean) out of FLL. Century only has balconies in their suite level cabins, so you're going to pay a bit more for the amenities in a suite.
Millenium and Constellation (M class ships) are more expensive than the smaller ships because they offer more amenities onboard (have not been on an M class ship......yet)
If you post which particular ship you're thinking about, maybe posters can be more specific with answers.
Good luck searching for your cruise!!