The Fireside Book of Folksongs and Great Songs of the 60s were the only songbooks I ever saw at home until I hit my twenties. The first, especially, rates a 10 for nostalgia value alone. If you know the Stan Rogers songs, then Songs from Fogerty's Cove, is a pretty good introduction to a few picking patterns and DADGAD tuning for the guitar. OLGA (www.olga.com) is a great source for song accompaniments if you already know the melody. I still think I haven't yet learned the melody to a single song from a songbook.
The only time I don't think Rise Up Singing is fantastic is when some beginner makes a request for a song from RUS and a normally fine musician proceeds to try and sight-read a very mediochre version of the song. Requests in song circles ought to be limited to songs SOMEBODY is very familiar with. Also, its simplified guitar chords often allow or even encourage simplifications in wonderful melodies. Song for song, RUS is terrible. Pound for pound, it's the most efficient songbook ever.
Joe: thanks for the pointer to Carl Sandburg's songboook. I'll have to keep an eye out for it. Why, oh why don't they reissue his albums?