re: What to do around Montrose/Gunnison, CO

For such a long duration, go at least twice: EARLY Oct, and again around Christmas.

Black Canyon, Grand Mesa, Million Dollar Highway, Mesa Verde, Hwy 149 from US50 to Lake City, Creede and South Fork is a great drive too - more fun on a motorcycle though. From South Fork head west on US 160 to Pagosa then over Wolf Creek Pass to Durango then North on US 550 make a nice loop.

Early Oct can be iffy with snow in the high country but if you get there early enough and the snow holds off you should drive Engineer Pass and/or Cinnamon Pass from Lake City to Ouray and Silverton respectively - won't need 4WD if it's clear but will want high clearance vehicle.