I was wary of going with the first tour company that I met on the beach, but after doing some research and realizing that pretty much every tour company offers the same stuff, we just went with them. We were able to bargain down some of the costs as well and the more people who came with us, the cheaper it got.
We did Helicolones, which started off with a trip to a waterfall that was very nice, but a LONG hike up/down some very slippery rocks. I thought it was pretty dangerous and didn't get to enjoy the waterfall as much because I was so tired. Then we went to the Puma Rescue area. This I liked the best - we were the only ones there and we saw beautiful birds, monkeys and wild cats. The cats were very tame and playful, they walk right up to their cages and you can pet them. Next we went into the mountains to do a rainforest hike with hanging bridges. It was a much easier hike and the bridges were a lot of fun, but not if you don't like heights - they are very wonky! I like danger though :) We had a typical Costa Rican lunch which was delicious and filling, with fresh passion fruit juice mmmm. Our guide was very nice and knowledgable and helpful.
We also rented ATVs with them, although this was a third-party transaction really. But the ATVs were well worth it - we went alllll around the jungle and the beaches, and we also added the canopy zipline tour to have a break in the middle. That was fun too - not a very long experience for the ziplines, but fun and the lines are awesome, you fly through the jungle and listen to Howler monkeys, and the guides are a lot of fun.
I'd recommend this tour agency, they are easy to deal with and their prices are pretty decent. They are also very professional.
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC.