Here is my opinion, and you should know I have never been to the UP that time of year. But when I think of Fall colors I think of the wide panoramic vista overlooking a nice valley tree tops... Eastern side is nice but much flatter overall. There are still some great vista to lookout over for that impressive viewing experience but I think less overall if you trying to make a trip out of it. Also if going by Tahquamenon Falls of course the falls themselves.
As wiscrev and whitedust said, Brockway Drive, Copper Harbor and there are a ton of falls in the UP. Here are some other spots I know would have a great view.
Eastern UP
★★★★★ · Scenic spot
goo.gl
Lots of Fall use Google Maps
Western UP
★★★★★ · Scenic spot
goo.gl
★★★★★ · Scenic spot
goo.gl
Northern LP
Topinabee Rest Area 407, I-75, Cheboygan, MI 49721
★★★★★ · Park
goo.gl
Northwest LP
★★★★☆ · Scenic spot
goo.gl
Main parking area -
https://goo.gl/maps/CkxpH6Gw1ayPdezZ7 (So when you open this link it says Low Bridge. There is a road that is right at the top of the hill on low Bridge Road just to the North of the actual bridge. I believe it is National Park Camping area there are some amazing views here. Easy hike from the parking area if needed but I think it can all be driven. But I've only been in winter...)
The actual overlook -
https://goo.gl/maps/ASyv1z6x3XKpnd8m6 When your see it there is a very visible dirt road which I think is Pine River Road.
Main parking area -
https://goo.gl/maps/fZZrwKKtj2eVU9yh7
The actual overlook -
https://goo.gl/maps/QaLshmbxA3LWj7tD8
Now this is not "where" you asked about, but it is "what" you asked about... It would also fall into the Mid to late October timeframe you asked about.
Brown County, IN (Think of the Smoky Mountains on a small scale)
The State Park has lots of viewing areas:
★★★★★ · State park
goo.gl
Also check out this Hard True. They have a very cool setup even with a 21+ ATV tour, or some music in the back amphitheater.
★★★★☆ · Distillery
goo.gl