I think I'd go for option 2. I'm not familiar with the SC part of US 221, but it's as good a road as you'll find going into the mountains in that area. There's no point in going via I-26 & I-40; you'd have to a serious climb on 26, and then give it back on 40, then climb again on 221.
I'm assuming you plan to go up US 221 to the Parkway at Linville, then double back to Spruce Pine? That's the way I'd do it in tow. NC 226 looks like a short cut, but it ain't. It runs more-or-less north from US 221 directly to Spruce Pine, but the last 3+ miles is a heck of a climb, with tight curves. The truck warning sign going down (south) on NC 226 from Spruce Pine:
Jim, "I've found my Sleep Number. It's seven. Seven beers."
