Yeah, I've tried the Farcry 3 split-screen and wasn't really impressed (though it probably didn't help my cousin kicked my ass for every time there was the racing-get-the-bombs mission

).
I was thinking about Borderlands 2 and I saw its substantial change over the first one but I don't know if she'll like it given the disappointment of the first one for her (which was pretty bare bones in terms of story/content).
Does Little Big Planet Karting have up to 4-player splitscreen? I know the other first 2 allow up to 4 players on the same screen but I don't know about Karting in particular.
Thanks for the suggestions so far, I'll be looking into a couple and see what I can come up with.