if you're on here asking this kind of question, sounds like BOTH of you have a lot to learn about riding/motorcycles. the whole "guy-getting-chick-to-ride-her-own-bike" is one of the more tired motorcycle stories.
if you don't know the difference between a 100cc bike and a 250, 500 or 650twin...it might be time to take a break from playing teacher to a novice and learn a few things yourself.
don't mean to come off harsh, but just callin it like i see it.
a lot of guys on this site have been on every displacement bike and find themselves coming back to a fun little bike. every bike is perfect for its own niche.