You've already received some great and true advice. traveling alone doesn't have to be stressful or boring... and that usually means getting to know other people... but be careful and use common sense... don't let yourself be drawn to something you don't want to...that doesnt mean you cant talk to anybody, no no no... just be extra careful as traveling alone really draws the attention of the locals... :)
Costa Ricans are very friendly people, and they will start talking to you, and sometimes they will even get very "friendly"... I know my men here :)... LOL.... so just use common sense and you'll be fine
Depending on the kind of hotel you're looking for Playa Negra Guesthouse, Pachamama would be worth checking out... and if you want to go further south and experience a different kind of lodging just by a beautiful golden beach, Almonds & Corals.
Gracias