Blitz,
You should really do a search before asking a question like that. Some of the fellas might get upset for not doing your homework.
But I'll help you out. First off, I assume you know that Jaco is the hottest place on Earth.
The humidity was unbearable for me. The chica action is not nearly as good as San Jose. During the day, it's virtually non-existent, from what I saw. I have read about guys finding chicas during the day though. With that humidity and temps, you don't want to be out looking for pu*sy during the day anyway. At night, the humidity still sucks, and there's really only one place to go, Beatle Bar. At like 9:30-10:00 on most nights (Monday sucked), it gets pretty packed. There is a good selection of chicas and, of course, the price starts at $100/hr but can be talked down some. I didn't see anything happening at Monkey Bar.
As for hotels, I stayed at Paradise Hotel. It's a budget type of place. It's $35/night. I would not stay there again. Although the staff is very helpful, I like to have a little more in my hotels. The Copacabana has gotten good reviews, I will try it my next time. No chica fee at Paradise, I think Copa charges a small fee (not sure though). There are a few other hotels that I don't know much about. Do a search.
Hope that helps.
-Orange