Congratulations on your impending Civil Union, do you live in New Jersey or Massachussets? 😛
Seriously though, the iPod works on simplicity, plus you can give her (yuck) ITMS giftcards as future gifts.
As Bootprint asks, if she has had other non-iPod players previously, the Sansa would be a breeze for her to use.
Also, if she goes to the gym, the FM tuner is a must have if TV audio is broadcast via FM, like at many gyms.
That said, I love my 6GB Sansa, it really is the best bang for the buck player out there.