There is no need to limit your musical interaction with Erin to your infrequent visits. One of the coolest gifts you can give her is a tape of you playing and singing. Audio tapes, video tapes, whatever. Sing your favorites, include her favorites. :-)

I've been trying to get my dad to do this for my son, but he's "too busy" so far. I have an audio tape that is very dear to me; a storyteller friend of the family sent me a tape when I was twelve, of stories and poems we had shared when I was little. The fact that I still have it nearly 20 years later should tell you what it means to me.

And I'd say go for the drum idea. Chances are Erin is already driving your kids bonkers with the pots and pans. Xylophones are a great idea, and harmonicas are a possibility at this age as well.