The February weather in Chicago can be as bad as Boston, and you can add in a vicious wind-chill factor. Decent choice for spring, summer, fall, but avoid winter. I lived there.
February is not the best time of year to visit any major North American cities with the exception of Miami, Los Angeles or San Diego. Boston will freeze your tits off. Do not under any circumstances consider Dallas - you'll be bored after half a day. Vancouver is a great city, but probably not...