They love the Guitar and learning sounds. I like playing scales to start blues and pentatonic. They light up. When I play basic chord progressions repeatedly they both bend their little 1 & 2 year old legs and dance. I broke my e string jamming out in their play area (getting pretty crazy and loud because I can sing passably well) and their faces were pricelessly shocked when it all came crashing to a sudden halt. This is all I've been using the guitar for lately however it's not a bad thing because it keeps your hands a going and you can get oddly creative around children with lyrics, chords/picking all while missing a guitar string.
GoatsShadow Out
You have the best audience in the world, and the best reason for playing.