Absolutely enjoyed our stay in Las Catalinas at Plaza Carlotta #8. If you're unfamiliar with Las Catalinas, it is a walkable town on the beach with beautiful hiking around. Snorkeling was a blast and reasonably priced at Pura Vida Ride. If you do snorkel, I'd recommend doing so at Playa Dantita, or walking to the far right of the beach.
The only negative I have to say is, if you are not from Costa Rica, DO NOT DRINK THE WATER!!! The welcome book says the water is drinkable, but everyone in our party got sick and we strongly believe it is from the water. Buy bottled water for your entire stay or you may end up not having such a pleasant vacation.