Having played in an Irish/Celtic band it seems the audience falls into 3 distinct camps 1)Hail Fellow well Met 2)Serious listeners and 3)Regular folks. There's a book/cd compilation called '130 Great Irish Ballads'(of which very few are actually ballads). It was compiled by Robert Grogan and is published by Music Ireland,61 Grosvenor Square,Rathmine,Dublin 6,Ireland. Probably available through any book or music store. Covers quite a bit of ground and most of the 'pub songs' are contained therein. Writing down requests is a good idea, but ask further as far as sources go and you'd be amazed what people will unearth for you. It's difficult to please everyone(you included)all the time, but as the previous post states if the music is played well most people wont know or care if it's an Irish tune or not. You may want to add Loch Lomond, Brown Eyed Girl and Dirty Old Town if you don't already play them. They seem to get a good response no matter what the crowd. Good Luck.