If you're coming back through Colorado (I'm assuming you'll already be at the Canyon tonight - it's a long haul), and that we didn't see you at the [wet] track day yesterday), 550 between Durango and Ouray (particularly the segment between Silverton and Ouray) is a must - BUT - don't drive it on wednesday, June 15th - that's Ride the Rockies, and 2000 bicyclists plus support vehicles will be riding from Ouray to Durango that day. Seriously. If you have to get from Durango to Ouray that day, take 141 over Lizard Head pass past Telluride, there will be MUCH less traffic.
The entire Durango - Silverton - Ouray - Telluride area is amazing. Rent a Jeep or take a Jeep tour (most of the trails are open except Black Bear and Imogene), the backcountry in unbelievable. We had snow in the high country last night, looks like snow level was around 10,000 feet, but the new snow below 12,000 will probably be gone in a day or so. I'm at 9K and we didn't get any new snow.
North rim of the Canyon will be cool (as in gorgeous)- many less tourisits, about 1000 feet higher than the South rim. You usually have to be there pretty early in the day to get a campsite, though - might have to stay at Jacob Lake and get into the park campgrounds the next day, unless you have reservations. Be sure to hike down into the canyon some - you can't really appreciate the size from the rim - but be careful. The canyon is different (the tough hiking is at the end of the day, the reverse of mountains), and can be dangerous if you don't take enough water, or aren't used to the altitude, which is around 8,000 at the north rim.