If in August, look up Black Bear Pass opening (Telluride to Ouray) to match up. Its only open few weeks during the year due to the snow fall on very top. Its not considered hardcore, but views and narrow ridge trail can give you a new take on where you are relative to NC.
If you are going that far in travel, stay in CO. Then following year, hit Moab for a week.
If you make a trip to Moab, 2 trails right outside end of town are Moab Rim and Cliff Hanger. If you want to hit a harder trail, Pritchett Canyon is on same road west out of town, but its return is a long ride back. Many do another trail (Behind the Rocks) on the way back from Pritchett. Then there is the BFE area! Another great place to go for 'hardcore' in Moab.
Check out http://www.rr4w.com/
(RedRock 4-wheelers). Their info on trails is very supportive (http://www.rr4w.com/trails.cfm
Since you can make a run back through CO in center CO, then hit up Buena Vista Carnage Canyon. Great way to end the trip.