for anyone who has been to s.f., or looked into going, you know it's a little pricey. even the most budget, ghetto hotels still cost at least 75$ a night & that does not include parking...so add on about another 30-50$ a night for parking. it adds up. this was the biggest issue for austin & i when planning this little trip of ours.we had really been wanting to go to san francisco, we had our hearts set on it, but were not willing to pay that much money for a gross, possibly dangerous location, ghetto hotel.i also have a weird thing about hostels in the states... i don't trust them. it just seems weird to me. so, we turned to air-b-n-b! 
i had first heard about the website a few years ago, telling me the next time i backpack through europe to check it out. then we had some other friends who used it when they went to europe this fall & said that it was awesome. so we checked to see if it was just a european thing, or if people used air b-n-b in the states, & they do! we were pretty excited about it & it's seriously an awesome way to travel.
what it is, is a place that people rent our rooms in their home, sometimes their entire house or apartment, or a private part of their place to travelers. it's basically a nicer hostel (at least thats how i look at it)
it's easy to find a place to stay too. just go to their site, type in where you're planning to go & a bunch of different spots pop up to check out. whats really cool is that people leave ratings & comments, & hosts want good ratings & comments, so it's super easy to find the good places to stay. you can also narrow down your price limit, & rent a spot by the night. 
we really lucked out in finding our place in s.f. neither austin or i were thrilled on the idea of renting a room out & sharing a kitchen &/or bathroom with a stranger. so we were really excited when we found a studio apartment. we had seen a picture of the place before renting it, & it looked cool, but we both sort of thought the picture might have been trying to make it look better than it was (i don't know why we thought this), but it totally wasn't. it's such a cool place. it's super nice, we both love the setup & it was really clean. it's part of a house that they made into a studio apartment on the main level & we use the main front door (which i think is cool for some reason). it has a family room area, queen bed, dining table, mini kitchen, & bathroom.   it has a great location, that is close to everything we've wanted to go & see, plus, it gave us free parking which is awesome.
entrance to the apartment 
family room area
kitchen/dining area
the kitchenette
they had a lot of cool books for us to look through 
dining/bedroom area
& the little bathroom
all in all, i would completely use air b-n-b again & totally recommend
it to anyone thats wanting a cheaper/different way to travel!