You need to look through posts on what to do in Belize. There are jungles, cave adventures, Mayan ruins and world class snorkeling as well as only place in the world to go cavetubing. A lot of people split there time between San Ignacio and either Ambergris or Caye Caulker. The Reef is off shore and I’m thinking Ambergris May be better (although our favorite is Caye Caulker. We just got back in Feb from CC and am heading back in May.
Instead of 1 house you may want to think about several condos that are together. Last year we went with 14 total and got 3 Condos at Caye Reef. It’s on CC and fantastic facilities and location. There’s only 6 units. Each are 2 bedrooms, 2 baths.
Grt house and area for both sea and mainland. Do it!