Animaterra (& others):

There are the week-long events like the Pinewoods camp in Plymouth, Massachusetts, but there are also weekends sponsored by the Pinewoods Folk Music Club of New York City (a diffeerent but related organization), often held in Falls Village, Conn. or similar places. The fees of about $100-$150/per person include food and lodging for the weekend.

Also, if you get involved with your local folk-music club, you'll discover other opportunities through their newsletters--singing weekends that, like house concerts, aren't publicized widely to the whole world.

-Charlie Baum