GA/TN/NC
Way too many roads to list. Currently in Atlanta, used to live near Asheville, NC. North Georgia, eastern Tennessee, and, of course, western North Carolina all have great roads--as good as any I've seen in the world. Blue Ridge Parkway. Dragon. Cherohala Skyway. Any twisty road to get up to the BRP.
Lots of local roads that would take me way too long to type. Almost anything on this map, for instance:
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Two personal favorites are 226A up to Little Switzerland...
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...and 276 up to Caesar's Head.
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Bear in mind, I haven't driven any of these roads in the BW yet, only on the motorcycles. I can't wait to get the BW up there. It's possible that the 5BW won't like the twisty stuff that the motorcycles do, but I have some other roads in mind for that as well. Time will tell.
CA
I've also had the pleasure of riding many of the great roads near Silicon Valley in California while living out there for work, on the ridge west and southwest of San Jose. Also as good as any roads I've seen anywhere. Just pick almost any twisty road on this map and you'll have fun.
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MI
When I lived in Michigan I found M26 bobbing and weaving along the Lake Superior coast to be a really fun road.
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