My wife and I snorkeled at Shark Ray Alley two years ago and are returning in January. We loved it. The 45 minute speed boat was fine but the snorkeling was FANTASTIC! I still refer to it as my favorite snorkeling trip. Lots of rays and fish and a few nurse sharks.
We went to a nice resort for lunch. My wife and I love eating local so the chicken, rice and beans was great especially with Marie's hot sauce (made in Belize). Nothing fancy but good and local. Beach was great but don't miss a trip to San Pedro the main town on Ambergris Cay. It's a small town with small shops and restaurants. The roads are sand and most people get around in golf carts. Buy some of Marie's hot sauce in one of the local markets it's MUCH cheaper than at the hotels or shops.