Agree with swellinfo, the daria is real nice for in Tamarindo, but I would only stay there a couple of nights then go somewhere else. I stayed at a place in Avellanas, but it is kind of boring there if you don't surf, so we had to go elsewhere to keep wifey happy, same deal in Negra.
I would definitely recommend Monteverde and do the skyline tour. It should especially be cool in January, no rain but cool weather. You can see the Pacific from up there on a clear day.
Rent a car and drive around. Explore the beaches around Tamarindo during the day and then go to Monteverde or another beach. Quepos/Manuel Antonio possibly.