'Neato - your methods sound a lot like ours. Our current incentives for DS involve Pokemon cards and "fun" computer time. They vary every few months or so. DS loves the fact that the challenge becomes a game.

Our Suzuki is set up like acs' too. Weekly private lesson and monthly group for piano. Violin has group almost weekly (even a bigger commitment!)

Both my kids took a kindermusik style class from age 1 that I think really helped pave the way for music lessons. The last class especially was wonderful - teaching beginning music reading concepts and trying out many kinds of instruments, learning about instrument families, etc.