I've been to 19 and lived in 5, so I feel completely authoritative when I say you should really avoid Philadelphia at all costs. (It's where I grew up.) ~~ • ~~ And hey, kiwi? Why do we have to type in the "DC" for "Washington"? All other cities are accepted as-is.
It used to be where pretty much every Western movie was filmed... it's also an International Dark Sky area, and is home to the only McDonald's in the world with turquoise arches instead of golden arches.
Surely you can think of a better clue for Boston?!? Like, site of a Tea Party in 1773, or a Massacre in 1770, or home to several elite universities, or anything other than "it's big and in Massachusetts, I wonder what it could be". Every other place on the list has a defining characteristic, except Boston ;(
I've been to all but six of these places.