Hey guys, sorry I'm late to the party here, but I'll offer any advice than I can. I'm almost out the door here and have to meet the wife soon for a dinner date (can't be late for THAT!) so I'll be brief, and then check back in to see if I can expand further if needed.
Concerning general vision with ski goggles and a need for Rx correction there are a few issues to consider:
Remember that not all goggles are created equal, regardless of initial perceived fit. The lens quality can really be all over the map, to say nothing of the rest of the frame and strap construction. You will get what you pay for in almost every case.
Almost all OTG style goggles will be larger. That's in order to fit as many spectacle frames as possible. The bigger the goggle frame, the more frames you accommodate, and the more sales you will generate with a given model. The nature of the beast means that if glasses are indeed your girlfriends only true option, then a larger goggle may be the tradeoff. There is often a small amount of compromise with these sort of systems, but it will be up to her if that level is too much to enjoy the sport both comfortably and financially of course.
Concerning contact lenses, there are a h-u-g-e number of lens styles that any qualified optician/optometrist/ophthalmologist can try to maximize quality of vision, and most importantly on the mountain perhaps, comfort and minimum dry eye issues. There are in some rare cases eyes that just don't tolerate a lens well no matter what the scenario. However, my experience has shown that a successful fit is as much about the motivation of the patient as the skill of the prescriber. My suggestion would be to find and visit an optometrist (in particular) willing to work with her over time and to try several different options in CL's until she is perfectly happy. Bear in mind, it may take numerous lenses before the perfect fit is found.
Ultimately, the insert style of goggle is the easiest to mitigate dryness issues if contacts are simply not possible. As much as I like the integration, and as much success as I've personally had with the Smith Optics line, my one gripe is that they don't offer the smaller I/Os version in an Rx compatible style. Yet. I had a good long talk with our Smith rep this afternoon actually as he was in making sure our new goggles had all arrived in time for the season this year. I was asking about a smaller Rx option, and he said he wasn't aware of anything coming down the 'pike currently. But he knows I'm a bit obsessive about excellent on snow optics and promised to let me know if he heard anything internally.
Please do feel free to send me a note here anytime as I'm very happy to offer any and all assistance I can. If a phone call is easier as well, it can help to cover a lot of information in a shorter time than typing here. :) Whatever works best for you two.
Here's to a great season everyone!