I would DEF recommend staying in the treehouse at Black Turtle Lodge (Tortuga Negra) just outside of Pto Jimenez... this is on the Pacific side on the Golfo Dulce. Nico (ex-pat) is an amazing, down-to-earth and helpful host. We flew into SJO, then took a small plane (1 hr flight) down to Pto Jim. (DO NOT take a bus...say it's 12 hrs, but more like 16!) This is right on the doorstep of Corcovado National Park. We didn't get to go this time, but still saw all sorts of howler/spider monkeys and toucans/macaws, etc. The gulf is an amazingly biodiverse place... loads of dolphin and whales, as they migrate there. Went on a kayaking tour thru mangroves and in the gulf as well. Went to a really cool animal sanctuary across the bay...and a few nature walks. Food at lodge is really casual and delicious. We had a non-traditional turkey dinner a few Christmases ago. Each cabin is surrounded by flora and there are paths leading to your own private beach. I want to go back. It is definitely worth it.