PegThat's a few good suggestions alright!
M
Listen to a few of the great female interpreters of the general kind of songs you think you might like to try. (The O'Domhnaill sisters sing a lot together and might provide some useful ideas for harmony)Apply your own standards of taste and risk-taking to them - don't be afraid to challenge your audience now and then. Slowly build up a repertoire that allows you to pick a suitable song for varying circumstances. Yes, you need a couple of easy-listening songs for when you're expected to sing even though you know the audience aren't likely to pay much attention to something more demanding. After a while, you can sneak 'em up on them!
Try that and I suspect Antóin's worst fears will never happen!
Regards
p.s. Even the dreaded "Wild Rover" has its charms if you use one of the earlier, quieter, rather rueful English versions!
p.p.s. You might also try a capella unison - there's a tradition of it in Irish singing and it can soouind beautiful.