Visit Chicago in the late spring or summer only. Fall may be fine, but the year I lived there it was winter for 3/4 of the year and I’m only exaggerating a little bit.

Philly is close enough to hop on a train (or a bus if you must) and do a quick weekend trip. Any of the others I would save for a long weekend at minimum, just because you’re spending longer getting there. Once you’ve been to NYC a few times, you can do it for a shorter weekend or even a very long day trip (I have done this, though I don’t actually recommend it).