IMO, Philadelphia rivals Los Angeles in having the most-attractive (and distinctive) street name "blade" signs in the United States.
A friend told me that the City of Brotherly Love is going mixed-case on those signs, and that sparked a discussion about the font that Philly currently uses (some examples here (http://www.philadelphiaspeaks.com/forum/history/28917-history-philadelphia-street-signs.html)). EDIT: This page (http://hiddencityphila.org/2013/06/signs-of-change/) has an example of the new, mixed-case Philadelphia "blade" signs.
Are they using a variation of one of the FHWA fonts now?
That was a very nice, long article about everything one could ask about those street signs!
I love the street signs in Philly, they're standardized throughout most of the city (some of the narrow alley streets still have the old ones) and they make navigating the city an ease, especially if you can orient yourself with Center City.
Per the linked-article, the font on Philly's street blade signs is now Clearview. The switch to this font actually predated the 2009 switch to mixed-case lettering which explains why there are some relatively-new all-CAPS street blade signs that aren't in FHWA font.