The three areas are totally, totally different. Ambergris Caye is the # 1 visitor destination in Belize with the biggest choice of hotels, restaurants and recreational activities in the country. That's either good or bad, depending on how you look at it.
Sarteneja, by contrast, is one of the least visited areas of Belize. Until recently, you couldn't even get there without driving on dirt roads for most of the day. There are a couple of guesthouses but other than that really almost no tourism infrastructure.
Corozal is somewhere in between. There are eight or nine hotels, a few restaurants and a growing but still small expat community. There's very little beyond a couple of small ruins and a tiny museum to see. It's on a shallow bay, not on the Caribbean Sea. Most of the visitors there are just en route from Mexico or are shopping for property.
Actually, the better alternatives to Ambergris Caye would be Hopkins or Placencia on the southern mainland coast, or Caye Caulker.
--Lan Sluder www.belizefirst.com