laurie, don't forget "barb's belize". she does only belize, and i hear she is great. she has a website you can link from the home page.
i chose to plan all my stuff myself, (even when i did my 10 day inland trip) then went to the TA just to book everything. i got travel insurance too. the $75 was worth peace of mind. debbie did too, and when Storm Alison hit houston and she was stuck in the airport, she received refunds for missed days at the hotel etc.