If you’re a surfer I’d head to Santa Teresa. Otherwise I’d suggest Montezuma for 3-4 days. Both areas have much prettier beaches than Tambor’s gray sand. There are public buses from Tambor to both areas but you may need to change in Cobano. Don’t rent a car as this is rainy season & most roads in the area aren’t paved. Either rent an SUV or just rent a quad for a day to explore.
Just to add to crfan's post, there are many more shops and restaurants in Santa Teresa, though it is still rustic.
Personally I would not want to spend 3 nights in Montezuma knowing Santa Teresa is nearby. I would use the transport methods mentioned and go to Montezuma in the daytime.
If you really want peace and quiet then spending the nights in Montezuma would be good.
Why not stay in Tambor? Tango Mar has a beautiful beach. You will love it there. You will also be close to Curu and Tortuga Island. Tango Mar has a waterfall and a golf course. Birding is popular in the area. You can also go horse back riding. You will be close to Montezuma, which has a butterfly garden and a zipline. I love Montezuma, but parking there can be a problem. Or you can stay at Tambor Tropical, but the beach there is not as nice. TT does have a sea turtle project on the premises, and the manager there is very much into birding, sea turtles, and conservation. I do recommend renting a car to get around. Feel free to PM me if you have any questions.