If doing Cinnamon Mountain alone from the pass, total roundtrip distance will be no more than 1.5 and elevation gain will amount to only 700 feet. If you include UN13,535, total mileage will increase to 4.5 total and 1,450 total elevation gain.
From Cinnamon Pass, walk south across tundra following a well-used trail that passes by some old, collapsed mining structures. This trail will then veer west as it climbs up to the saddle east of the summit of Cinnamon Mtn. As it heads for that saddle, it cuts across a very rocky slope and you may encounter just a little talus scrambling just before gaining the saddle. Once on the ridge, head west for an easy walk-up on rock, soil and tundra to the summit. Return by the same route or continue over to UN13,535 by following the ridge back east to intersect the ridgeline that generally heads south to UN13,535. Total roundtrip time for Cinnamon alone 1.5 hours. If you include UN13,535, 2.5 to 3 hours.
Bonus points: For those wishing to make this peak a more "sporting" climb, try starting down around Animas Forks and hike up the west side of this mountain on mostly steeper, tundra slopes for a 2,500 foot gain.