I drove RT 191 from Springerville, AZ to Morenci, AZ. It had so many turns it made me motion sick after 2 hours of non-stop turning at 25mph. I was in a lotus. I could have gone faster, but the road rides the continental divide. I didn't want to go faster. 3 or 4 hours for 117 miles and it's well over 318 turns.
I concur with your fellow Michiganders that you are already in a great state for road trips. One of the best road trip caravans I have ever done was with a couple from Grand Rapids Michigan. Cruise all the lake shores and the many other attractions in Michigan.
For some of the best motorcycle (and therefore Porsche) roads check out this website:
https://www.motorcycleroads.com/ It will provide you with a lot of wonderful roads that you and your Porsche will love. Even my Fox has enjoyed several of these roads.
Be aware though that the police are also very aware of great driving roads and will often be present and watching for us goof balls when we stray across the centre lines.
M-119 Tunnel of Trees, north of Harbor Springs, MI. For more of a road trip: Smoky Mountain National Park / Gatlinburg TN area has a bunch of awesome twisties.
I don't mean to brag or anything, but Montana has many wonderful drives that are typically wide open and wonderful. In particular is Hwy 89 which runs from the northern boundary of Yellowstone National Park to the Canadian border. The mountains and plains along the way are spectacular. However, word of caution, don't drive in early to mid June as ranchers use many of the two lane highways to move cattle from pasture to pasture ( a few miles at a time. I don't know about you, but trying to get cattle poop off the bottom of your classic is like trying to get dried concrete off your shoes. Cheers and Drive Well.
I can't argue with anyone who suggests the great roads in the Smokey Mountains. But for great roads and scenic beauty, the Finger Lakes of western New York State is worthy of a nod. Toss in a number of fine wineries, charming villages, and skilled craft creators and you get a combination that is unmatched east of the Rockies.
If you get to Central Texas, try the 3 Sisters. It's not Tail of the Dragon, but not too bad either. And you may see an exotic (McLaren, 911GT3, Mercedes AMG, Ferrari...) or two on the way.