I was all over in Costa Rica, and I absolutely LOVED it. I went in November (which is an important detail, because it was the tail end of the rainy season. Everything is cheaper then, but you will most likely get more rainy days than dry ones...but it doesn't always rain all day.) I especially loved the west coast town of Santa Teresa (near Mal Pais), and the southern town of Quepos, which is near Manuel Antonia National Park (it's a rain forest). We stayed at a hotel owned by witnesses in the area. The food is great, and the bethel branch is awesome. You can get by with knowing little to no spanish, but it's def. a plus. If you want to explore or relax, CR is the place to do it.

I've also been to Belize in March, and... it's wasn't nearly as pretty as Costa Rica. But if you have can scuba dive, Belize has the Blue Hole, which is like the #2 dive spot in the world.