Hmm... I would have to say just about any location from the Midwest into the Northeast.
But, I'm going to have to narrow it down to Michigan's upper penninsula. It's absolutely beautiful up there, and almost makes me want to move up there full time. The summers can be hot and humid with plenty of sunshine. That makes for good hiking through the forest, through the "mountains", and along the fresh rivers... The population density is very low, so you don't have to worry about polulution, smog, or running into other people - it's just you and nature (sometimes a little TOO much nature with horse and deer flies the size of quarters, LOL).
The fall features very intense colors, which can be viewed from the tops of very tall hills/small mountains - which give you a view for miles upon miles of rivers, forests, lakes, etc..
Winter has plenty of snow, averaging over 250 inches per year at some locations - so you definitely hit that season...
Spring features the melting of the heavy snow pack, which gives way to flowers and a nice mild breeze... Leading into summer (and then repeat).
Even with my intense passion for severe weather - I just couldn't permanently move away from all of this scenery, only to be replaced with miles of corn and wheat fields (and little to do in the "off season"). If you're into nature, photography, old architecture, and "outdoors" stuff like dirt biking, hunting, fishing, boating, etc.. - the U.P. is one of the best places to be.