Given what Nick has said, I think a music session is probably the way to go. A group of musicians playing "in the background" is likely to be a draw for some and could help to attract punters to the pub. The players themselves are mostly there to enjoy themselves and to take an opportunity to play with other like minded folk. If that is the case, then everybody is happy.

It is a pity that for some that playing and singing are seen as mutually exclusive activities. I think that is their loss. I like to do both and go to both sessions and singarounds (if that is a correct plural) and I find that there are a few singarounds who are quite happy for you to play a tune instead of singing when it's your turn. In an evening, if I get two turns, I will usually play a tune in one and sing a song in the other and that seems to go quite well at Folk Clubs I go to.

I agree, stallion, that singing choruses with a group is satisfying, but so is playing with a group of other musicians.