It sounds like you already have your tickets to Belize City. Is that right?
If you are more specific about what you want - bedroom/hotel room/ upscale/budget, etc? you will get excellent input from this group.
Marty has given you some very good websites. I absolutely love going into the various web pages through the link below my name. I find the research half the fun. I just get so excited looking at the beautiful pictures. I have found all the facilities respond quickly to e-mail.
For upscale I like to stay at the Tradewinds (pool, TV, bedroom, kitchen, etc.) For budget we will stay at Lily's. Mr. Felipe Paz has been very good at answering all my questions and helping with a problem.
Personally, I don't "book" side trips until I get there. You will have more help than you can handle. ENJOY!
Look at http://www.ambergriscaye.com/pages/town/town.html