Dennis, unless you need to store a lot of memory hungry video on the ipad, I'd say 16Gb should be ok if primarliy for music sheets, small library of MP3s, and a few ipad apps. It took me a long time to fill my 64 Gb model, but I've got everything except the kitchen sink stored on it.

If you to the 16Gb route though, I recommend AirVideo & Audio Galaxy apps, which allows you to 'live stream' video and audio residing (stored) on your desktop PC to the iPad (via wifi). Very cool & useful apps.