Pat Works On the Railway is a great idea! Pass out two spoons per kid and they can play along as well as sing. Hm, we do have some "clapping sticks."

Thanks for the suggestion of Early in the Morning - I found some of the tracks on Rhapsody and the track listing is useful. I think Paper of Pins may work as well, especially if I can talk a coworker into singing it with me as a duet... and I'll Tell Me Ma would be good too.

I have two picture books: St Patrick's Day in the Morning by Eve Bunting and Jan Brett, and Dear Old Donegal, illustrated by John O'Brien (too intricate for me to play and sing though). Another I'm considering is Over the Hills and Far Away, the nursery rhyme version of which I've found as a charming animal-character picture book.

The basic plan is:

Song
Book
Song
Craft -- depending on age, either paper clovers (Cut out three or four green hearts and connect at the points) or Celtic knotwork (which I've learned a fairly easy method for).

Extra songs and books to taste. I'm definitely leaning toward Rattling Bog and Paddy on the Railway as they're both participatory, but anything with a repetitive chorus ought to do. I've been playing This Old Man recently; the kids may not know it at first but their parents often do, and by the time we get to ten everyone is singing along with the refrain.