I do a lot of wedding photography here on Caye Caulker, http://www.flickr.com/photos/caribbeancolors/sets/866645
so I attend reception after reception after reception.
The most widely used facilities are Habaneros and Rainbow. For catering, the most widely used caterer is Barrier Reef Sports Bar.
If you are looking for an inexpensive but nice place for the rehersal dinner, take a look at Syd's on middle street, behind their main dining room they have a garden which is very nice, clean, new tables and chairs. Depending on how many people will be attending the rehearsal dinner, also, the SandBox has a big long table in front of it that can probably seat 15-20 people.
If the above link to my photography website looks like a shameless plug, believe me, it is.