Beaches resort in jamaica is awesome. all inclusive, crystal clear water,and 5 pools( with swim up bars). The only thing is that it rains almost everyday. The Bahmamas are fun but not as nice weather. Go to Atlantis or Beaches in bahamas. hope this helps. ask if you need anything else
have been all over mexico, guatemala, and belize. they are all ridiculously sweet. belize was the most expensive. i would think you could fly to cancun for super cheap, and from there, you can take a boat out to isla mujeres, which is a fun little island- beaches, snorkelling, bike/ scooter rentals, beachside bars, that sort of thing. south from cancun is the town of tulum, which has the most gorgeous beaches ive ever seen. a little further south and more inland is the town of san cristobal de las casas, which is a badass town up in the mountains with tons of local, mayan culture.
guatemala is dirt cheap, but maybe not the most family friendly? you cant go wrong with lake atitlan, though. or livingston on the coast.
belize is just the bee's knees. tropical islands. cheap rum. snorkelling with devil rays and nurse sharks and moray eels at the barrier reef. a bit pricier though.