Ambergris Caye has more than 60 hotels, and a number of them are really nice, upscale spots. You get can a fair degree of luxury starting at around US$100 a night, and go all the way up to US$1000 or more a night (at Cayo Espanto). Among the ones I think are special, in various ways, are Victoria House, Mata Chica, Villas at Banyan Bay, Banana Beach and Cayo Espanto.
Among the jungle lodges, my favorites include Ek 'Tun (best swimming pool in all of Belize, a natural mineral pool in the jungle), Lodge at Chaa Creek, Lamanai Outpost, Blancaneaux Lodge, Banana Bank, Chan Chich and duPlooy's.
Belize books and publications by Lan Sluder:
Belize First Magazine (http://www.belizefirst.com
Fodor's Belize & Guatemala Guide
Belize First Guide to Mainland Belize
Adapter Kit: Belize (the first and only comprehensive guide to living, retiring, working and investing in Belize -- a best-seller on Amazon.com)
UpClose Central America
San Pedro Cool (coming soon)