Speaking for the Northern Utah area, the tri-canyon area has a lot to offer. Millcreek, especially, showcases the Fall colors nicely. A hike to Lake Blanche Fork in Big Cottonwood Canyon will take you to 3 lakes mirroring Sundial Peak. I like the aspen trees in fall with their yellow leaves.
I would suggest a trip to Guadalupe National Park and Carlsbad National Park. The hiking in Guadalupe is fantastic and it's still fairly warm most days. You can get some fantastic views from the top of the peaks and Guadalupe Peak and Hunter Peak (my favorite) can each be done in a day. Another nice day hike is McKittrick Canyon where that time of they year you can get into foliage coloring up nicely. Carlsbad is only about 50 miles north of there and the trip in the cavern is great. You can stay in Carlsbad and make the drive to each fairly easily.