If I bought the gf a PS4 I wouldn't get a look in.
OP, right - you do it like this.
Make her something, anything. I'm building a display table so we can put sentimental stuff we've done together in the compartments (over in this thread
http://forums.overclockers.co.uk/showthread.php?t=18558767).
In the compartmentalised section, I'm turning it into a temporary advent calendar.
It's her birthday a few days before christmas, so I've got a variety of gifts that are going to be behind each door.
I've got tickets to the top of the Shard at sunset just before christmas, and some jewellery she has to open once we're at the top. Tickets for VIP/Directors Hall at Showcase Cinema. Spa Evening in bath. Assasins Creed Black Flag. PJ's. Music. Perfume. There's so much you can do. Just have a think!