No GPS for me. The Foothills Parkway is accessible in the middle of Wear Valley off HWY 321 or west of Walland on the same Hwy. It is and out and back ride for a distance of your own choosing.
The little river road from the Sugarlands to Townsend is pretty.
The road from the "Y" over to Cades Cove and the Cades Cove loop used to be nice. (35 years ago). I think auto traffic is disallowed at certain times.
The Cherokee Orchard loop in town was interesting, not too long.
I rode from Sugarlands up to Newfound Gap once, but you need to choose a time with less traffic. The coast down was a blast. No pedaling for miles and miles. Had to stop for a bear photo op.
The Maryland club hosts a Tour de Blount that went into Townsend. You might find the route on the web.