2 more cents:
the downsides to spontaneously called tunes:
• with BIAB tracks, if you've never heard the selected song(s) with a vocal melody, you have no clue how to play with the song, other than root chord noodling, or maybe gleaning some idea of the melody from players before you who DO know the melody.
• the whole format is solo playing; and I feel that playing is more enjoyable, for players AND other listeners (we do have an audience), when players are at least somewhat familiar with material.
• all of us play better when familiar with material.
• no one HAS to prepare, but if material is available, it's an option for eager-to-impress jammers
• there are quite a few new players, any help to them should be welcome, I'm guessing
• I still would love to hear a quick verse & chorus with vocal to refresh my memory; for the life of me I couldn't remember how "Bubbles in My Beer" went, till Groover hummed it to me, after my turn had passed, of course. Not all of us need that, but I'm sure that for every last song, SOMEONE needs or wants that. Otherwise they usually pass, and that lessens their enjoyment of the jam session.
• I envision a short list of pre-determined songs, as well as a set of requested songs, get it both ways.
So there!
I'm tempted to host a jam in this format if life ever slows down. I have many students playing our Perl Jam now, and I know all of them like these ideas to make it a more satisfying, more educational experience for them.
Professor Twang