Here we go with a re-drawn 2nd floor:
http://i115.photobucket.com/albums/n292/RedboXen/Fosters%20Big%20Fat%20Awesome%20House%20Party/secondfloor.png
It took quite some time to do, but it does sort of match up. Unfortunatly I had to scale it down in size to get it on Photobucket, but if you want the fullsize version, let me know.