Do you know a beach in Costa Rica with the below characteristics...?

My husband and I want to relax in Costa Rica; the perfect beach would be:

VERY IMPORTANT:
- no surfing, we want to be able to swim and enjoy the ocean without the big waves;
- white sand;
- not too crowded with people, especially turists. We don't want to get totally isolated either. Something in between, calm but with small things going on;
- my husband wants to snorkel; any good place?
- where to see those hanging bridges that float atop the forest? I heard Costa Rica has those.

IT WOULD BE COOL:
- rustic hotels;
- small town, with rustic/small bars and restaurants;

OTHER:
- are there any other airports besides the one in San José?
- I know it's the rainy season in CR in August. Does it rain the whole day or is it just tropical storm - heavy for an hour, then stops? 'm from Brasil, I know those... I gotta work on my tan, so I want to know if there's enough SUN in August :)
- any good hints about going out dancing good CR music?

Muchas gracias all!
Karina.