I've always wanted to visit the home place of Grunge. Those other two I've been to, and yeah... I wouldn't want to live in either one. lol I do enjoy the Field Museum, though.
Seattle is a pretty neat place. Lots of culture and interesting places to visit. Pike Place Market has bunch of cool flea shop goodies and fresh groceries and fish. The pier has bunches of cool shops and restaurants as well as ferry service to nearby islands. Tons of random independent cafes and artsy institutes and businesses. Unfortunately in downtown there's homeless and crime aplenty. Though it's been over 11 years since I've been there so I have no clue what it's like now.
LA is still the strange and beautiful place I remember it as, at least near Sunset & Hollywood blvd.
Chicago's loop is classy and expensive, but oh so grandiose and awesome. Even McDonalds looked like a top tier bank with it's huge windows and gold plated pillars.