Soundwave on 20 November 2012
If money is not a big deal, go for it. Co-op games are pretty plentiful on the system already, your girlfriend will like it if she likes Mario games.
As you said though you're a Sony fanboy, so you might want to make sure you are ready to pony up $400+ again next fall for a PS4 though too.
I do think despite Nintendo saying "no", the Wii U will be getting at least a $50 price drop before the PS4/720 come out next year. Obviously though I'm assuming you know the pitfalls that coming with being an early adopter.
