That's a good point about the graffiti.  The photos were taken twelve years ago and as I recall they were all "illegal" graffiti installations, all public spaces, nothing commercially sanctioned by the property owners and none marked with copyright symbols.  Ultimately I followed the Wikimedia Commons advice:

"Photographs of graffiti have long been allowed on Commons. As artistic works, copyright in graffiti will theoretically belong to the original artist. However, in many cases the artist is unknown, proof of authorship of the art is problematic, and, some believe, the artist would have difficulty enforcing their copyright since that would require a court to uphold the validity of an illegal act as the basis for damages or other relief against a third party."

There is one graffiti image in this collection that has the Ren & Stimpy characters, that could fall under trademark law.  While I've never been contacted about having it in this collection it's worth being aware of it.

Thanks for the great comments!