Great find! I hope you don't mind me adding to your thread, BigKidD, but I went around to some of these sites today to do a little then-and-now comparison. I didn't have copies of the originals with me, so I had to shoot these from memory. You kind of get the idea though.
Southwest corner of Market and Second
1918:
2007:
Market below Beale
1885:
2007:
Market between Drumm and Davis
1895:
2007:
Beale between Market and Mission
1890:
2007 (I'm not sure which side of the street is shown in the original, so here are both sides today):
Note: the old PG&E building (on the left) wasn't completed until 1924, so it not being in the original isn't much help.
Market between First and Second
1890:
2007:
Market and Pine
1890:
2007:
North on Montgomery from Market
1886:
2007:
Post/Montgomery and Market
1900 or 1902:
2007:
