The inter-mountain west, where aspens glow a uniform gold in contrast to the dark green conifers, brilliant on a sunny fall day. A sight to behlold.
Upper East TN/ Western NC (around Asheville).
Zion National Park
Fallen leaves and bare branches aren’t that beautiful, so say Autumn instead 
My sister and her family are there at the moment for the school holidays. She says the autumn leaves are wonderful.
The trees in Bowral, a town in the Southern Highlands of NSW, are all turning at the moment too and look spectacular.
Another vote for central and northern Michigan. Spectacular. And even more so on a puddle-jumper plane or hot air balloon ride.
My backyard.
If you don’t mind looking down instead of up, Denali National Park is spectacular in the fall. The berry bushes and other alpine plants turn all colors of orange, purple and red, while the aspen is brilliant gold. The image burns into your brain.
Yeah, Northern Michigan is awesome in the fall. It’s nice to see multiple people mentioning it, because it’s like confirmation that it’s not that you just don’t have anything to compare it to. 
And holy cats, you weren’t kidding about Cut River Bridge! http://www.hearth.com/talk/attachments/cut-river-bridge-jpg.75152/
Or Porcupine Mountain http://3.bp.blogspot.com/-AKRsDQ9jgsc/TmomBQVVchI/AAAAAAAAC0E/nz5MlfwWzco/s1600/fallpic5.jpg (Though I’m sure the color saturation has been kicked up a notch. But still gorgeous).
This page has a bunch of great shots: Fall in Northern Michigan: Photos & Trip Report
Northern/central Wisconsin/Minnesota, along the Mississippi river. Spectacular. Thank you for asking.
Agreed. My Brother lived in Bloomington and while it’s gorgeous year round, fall is really special.
I feel like I’m missing something. Don’t the leaves change color in the entire northern tier of the country (and Canada), if not also some south of that too? Do the leaves look markedly different from state to state where they’re north enough to change?
Obligatory video:
As mentioned, northern Japan, the Korean Peninsula, and Manchuria are analogous to New England: not far from the moderating, moisturizing effects of an ocean, but with a big, dry subarctic landmass to the northwest, perfect for causing quick drops in temperature come autumn.
West Virginia. Here’s a sample: Snowshoe Fall Colors 2012 - YouTube
This is the first place that sprang to mind for me, being a former Virginian. It’s absolutely incredible.
