I've been to both. Costa Rica is very high on my list and one of my favorite countries. I like Belize, too and it has a lot of English charm. Everything GW says, I echo. And, on the Caribbean Coast of Costa Rica, there is an area that has only had electricity since 1993 (brown outs every night, which is groovy in my book) and only had telephone since about 1997-98. They methodically, deliberately control their growth, have virtually no militia and enjoy a 93% literacy rate, which tells me they have more figured out than possibly we do. If you want mountains and jungle, volcanoes erupting everynight, Costa Rica is the pick~~~~~
Food is funky in Costa Rica, but I didn't starve. Food is fabulous in Belize - I gained weight! Keep us posted!! You'll have a blast in either place!!