I think Lan has given you excellent advice.
You might want to consider the area south of town called Mar de Tumbo Beach. This is one of the best beaches on Ambergris Caye and does not have a seagrass problem (turtle grass) as the wave action there tends to lessen the growth. Just walk in and go for a swim.
Located on this beach are several good resorts, but I suggest, as Lan did, that a condotel is probably the most appropriate type of accommodation.
Banana Beach with one bedroom suites is a great choice, and Villas At Banyan Bay with two bedroom suites is also an excellent choice. Each resort has a swimming pool, and air conditioning. They are near to very good eating places and beach bars.
The price of the suites will probably determine your choice as both are very nice. You can check them out at:
<A href="mailto:firstname.lastname@example.org">E-mail: Banana Beach</A>
<A href="mailto:email@example.com">E-mail: Banyan Bay</A>
Enjoy and if I can be of further help, please feel free to contact me direct.
[This message has been edited by Sandcrab (edited 05-01-2000).]