Livable cities for the college grad

Okay folks....I posted a question in the Quebec forum and in the Midwest forum but I want to get more varying repsonses. Within the next three years, i am planning to make a major, and hopefully permanent, move. By that time, I will have finished school so wherever I go from there, I want to make it my home. I want to be able to live in a city with GOOD and RELIABLE public transit. I don't want to live downtown, but with easy access to it. I want to live in a good but AFFORDABLE part of the city. Also must be safe since I am a single girl who would probably have no family in the area (most of my family is either in the Midwest, Southeast or Caribbean). I would prefer to stay on the East Coast, but would consider parts of the Midwest and MAYBE Seattle. I like cold weather/rain/snow.....detest hot weather. I have very minor sinuses, but nothing at all grave. I've Have already ruled out NYC because its waaaay out of my league in more ways than one. I want to stay away from the deep South (where I have spent most of my life) so we're talking VA and up. Any suggestions? Toss some my way and let me knwo why you suggested what you do. I have considered the following: Pittsburgh, Philly,Indianapolis, Chicago, Seattle, DC (BIG maybe....used to live near there), Boston.>