Just the obvious,
Hotel Del Rey for attractive freelancers
Key Largo across the street for not-as-attractive freelancers, but a band and more laid back environment
Zona II for daytime and early evening action. It's a bordello very poorly disguised as a massage parlor
Fogo Brasil is my favorite restaurant. It's a Churrascaria.
Best daytrip is to Poas Volcano. Take in the butterfly farm on the same trip.
Go to
www.costaricaticas.com for the most detailed mongering info.