Or would the 468-II be better because of the ttl?
The YN560 is a full manual strobe unit. I have the 468-II myself and I love it. The 468-II will set you back a few extra bucks but the iTTL will make it easier to use under most conditions, in my opinion. Just attach and go, basically. The flexibility is there to adjust/compensate if you (she) wants it though. Between the two, I'd suggest the 468-II but that's without taking anything away from the '560.
Also, since you're in this deep, go the extra mile and get her a decent diffuser while you're at it. She's going to want one and the
OmniBounce diffuser will work like a champ. With that, she's good to go and you score bonus-points out the whazoo.
EDIT: Yes, THAT particular Omnibounce. Even though it says it's for the Nikon SB600 it fits the Yn468-II just fine. It's the one I use with my 468-II.