In October, you will probably want to try Brock Creek Trail. It's well marked, but a bit rocky. Brock Creek is in the Ozark/St. Francis National Forest, and is approximately, 30 miles northeast of Russellville, 30 miles northwest of Morrilton, and 35 miles southeast of Clinton. (almost directly on the path of the TAT).
A map is available on the USFS web site. The trails are numbered, and designated atv and motorcycle trails. The perimeter trails are easier, and the "cross trails" are more vertical. Look here for a map: http://www.fs.usda.gov/Internet/FSE_DOCUMENTS/fsm8_042765.pdf
Another option in October would be the Bear Creek Cycle Trail along the north and eastern shore of Lake Greeson, 50 miles southwest of Hot Springs off US Highway 70.