Your girlfriend very well may have different taste than you in women, or even similar.
I will form my kind of woman I liked when I first started as an example. Note any man I've dated, (besides one client on a paid long term basis,) has not been into this kind of girl. Lucky me, he was!
I liked the long blonde hair, a little older, curvy, bigger frame, huge - fake - tits, tall, etc etc.
We picked one out and it was super cool for me. I felt so special that my present was a hot chick for a day.
Then I had a doubles partner who was even hotter, which made for guys getting a little less attention from me lol.
Now I have different shapes and sizes I want to try.
So maybe ask her what she's looking for and take her on a tour through different ads and pictures. And gave fun!!!!