a much as I will get hate on for this, a Buell Blast makes a good starter bike. Cheap, easy to find parts, easy to work on.
When she is ready to upgrade to something quicker, can turn around and sell the Buell for near the same price you paid.
I have to laugh when someone calls me an a*****e. I've been called far worse than that.
- Gordon Ramsay
I, personally, don't have an issue with the Blast or any other faring-less bikes, she just loves the look of a faring'd sport bike, so I'm against a wall on that one.
I have 3 friends with Monsters from various generations. I had her sit on one and it was just too big/heavy for her. Again, she's a toothpic and "feeling safe" is the first thing you want a newbie to feel and she simply didn't feel safe on one. Same with the touring bikes, just too big and heavy for her.
I'm sure after a summer with a 250 I can convince her to step up, but maybe she never will. What she does, it's her decision.
I wouldn't be as concerned with outgrowing a 250, so much as "outclimbing" one. I assume that there's a lot of good mountain roads in OR. A bike that makes about 20 HP at sea level would be quite a dog at 7,000 ft. I think a non-supersport 650 (SV, Monster, Ninja) would be a better choice. Since she's fairly tall, a 400 supermoto wouldn't be out of the question either, especially if it's lowered.
She often rides with me on the R1 and is still scared when I accelerate. It doesn't help that we live next to a neighborhood full of 'vettes and even a Gallardo, all of which like to play on the backroads near our homes. Of course, a vet wanted to play while she was on the back and I tapped her hands (which means "hold on") and I think she still pee's herself a little, even in straight-line acceleration. She's still in the habit of pressing her head next to mine (so I'm all sideways cockeyed) instead of trusting me and riding in-line, I'm trying to break her of that. BUT, it does mean she's very interested in controlling the situation by wanting to watch what's in front so bad. Still, she can't see herself on a bike nearly that powerful or even midsize sportbike (she hated my Gixxer750 and 929rr too). The other bikes that are a lot safer (the sv, gs'es, older sport bikes, etc.) she simply HATES the design of. I can't fault her for that, I'm the same way. Half my love affair of my bikes are the looks, the other half is performance.
She actually road one of my buddies Monsters (2004'ish?) around the block and when she stopped we had to keep her from falling over, she's seriously new to this stuff. And we all know what the typical dump is... low speed, in a parking lot, etc. etc. She's going to dump whatever she gets, but I'd rather it be a small, used 250 than a heavier bike that she'd have even less control over. One other problem with the Monsters (and similar) is that there is even less wind cover... your faceguard becomes the windshield - streetfighters are definitely a no-go for her. Even most sport bikes allow you to get out of the wind with a good tuck.
Your gf needs to understand that learning first on a cheaper, less beautiful-looking bike, will eventually lead to the experience of handling the higher end cc bikes (translate to much more beautiful looking). Put up with a used SV650s or some other used bike for a year or 2 and then move up to a bike in which she ideally wants. This way, when she does drop it, she could care less if there was a scratch or a crack on a fairing piece. You have an R1 so you know how dang expensive just a plastic piece is. Also, don't start her off on a Ducati...has she seen maintenance prices and even parts prices?