Most popular is Benham Trail -> Bill Williams Trail
Nice climb with never ending switch backs followed by a great fast flowing descent ending at the Williams ranger station. You can then hit the Williams Link or Clover spring trail to connect back to Williams and take Perksinsville Road back to the Benham Trailhead, making a ~18mi loop. Pics.
Bixler Saddle is an option on the west side of Bill Williams Mountain, it connects to Bill Williams Trail just below the top.
There's also the Sycamore Canyon Loop ~11mi. It's generally flat, rocky, and techy in spots. It skirts the edge of Sycamore Canyon and the wilderness area. There's several trailheads to start from but my fav start/end is at the bottom of KA Hill which makes for a fun ending for a sweet ride.