UVA has much more prestige than SFSU.

You should be able to rent a room near SFSU for $700-1000--even cheaper if you're willing to share a room. If you live further away and take the train in, you can get much cheaper rent, but the commuting cost, plus the time wasted commuting may not result in savings that are that significant enough to be worthwhile.

SF is a great place to live. There is an endless amount of things to do. There are beaches a few miles in every direction, great culture, great food, museums, interesting sites, etc. It will be a much more interesting place to live than Virginia. However, Virginia will put you in range of a lot of famous eastern cities that you can make day trips to, like NYC, Philadelphia, Washington D.C., etc. Don't get me wrong, there's a lot of things to do and see over on the west coast. But things are much more spaced out there. You can make weekend trips to L.A., Las Vegas, Portland and Seattle, but you'll be spending more of your weekend commuting than sight-seeing. But there are plenty of things in Northern California worth seeing, along with strong transportation infrastructure that will allow you to see it all. San Francisco and NYC are the two most exciting U.S. cities, in terms of culture. So if you are more interested in an adventure in a major American city, SF is the better bet. In terms of quality of education, I'd wager that UVA is probably going to be a bit better.

The weather in SF is very moderate the whole year around. It's also hard to predict. You won't see any snow, and we're in a drought so rain is not to be expected either. We get a fair amount of fog and wind, but it's not overwhelming. It's known for having slightly chilly weather most of the year, and then having a few weeks of warm weather in fall. Bringing a light jacket with you wherever you go in SF is usually sufficient to handle any and all weather conditions you'll face.