Exchange Zones

I would like to spend 1 month (+-) in San Francisco and I'm looking for a well connected flat.
If you're thinking on visiting Barcelona this summer we could swap our flats.

This is my flat:
- Well connected (15 minuts walking from Pl, Catalunya, the very city center of Barcelona; 10 minutes to train station...)
http://www.bcn.es/cgi-guia/guiamap4/cgi-guia/?actives=K001K002K003K004&zoom=1&scl=4&cnt=30822.310%2C83390.530&plt=30822.31%2C83390.53&plant=capes4a&txt1=&txt2=C.+d%27Arag%F3%2C+349&idioma=2&grayscl=0
It's in the city center but it's not a tourist center. If you don't like shops, markets, coffees... specially designed to tourists you'll be in the perfect place.
- It's also well connected to ride a bike. There are bike lanes and 'bicing' points everywhere in this area. (there is a new bike service in barcelona called 'bicing':you can take a bike in one point of the city and leave it in another point)
- 40 m2. Not so big... but enough for 1 or 2 people (1 bed-living-room + kitchen + bathroom).
- Placed on the second floor (with elevator)of a nice building. The windows in the front define a semicircle area where you can sit and watch the street. It's really nice.
- A little bit noisy because of the traffic in the street but July-August are quiet months, the traffic is lower than the rest of the year. Like everything in this world, there is a good thing: it's noisy because of the cars but you won't hear any shouts from neighbours or people in the street.
- The sun comes in the studio all day! I know that Barcelona is a place to live outside but it's nice to have a sunny place to stay inside it makes you smile...

What I need in San Francisco:
-I need an apartment just for me.
-The neighborhood is not important at all, the only requirement is that it should be well connected 'cos I'm not used to drive...
-I can take 20-30 free days from work between 7th July - 31th august, so, I have no closed dates.

Hope to hear from you.
thanks