Few years back on a KLR tour of the SW I rode to Monument Valley from Page, AZ. Even though I grew up in AZ I had never made the trip to Monument Valley. Had a great time riding the KLR through the park, except for my geologic error: when sandstone formations erode, the roads are....sand.
A fully loaded KLR with highway tires filled to 28 and 36 psi made for some interesting moments, but I always stayed upright, somehow.
Goosenecks of the San Juan River and the Moqui Dugway were great, too.
And I took the GSA to Canyon de Chelly two summers ago. Wow.
Southern Utah and Northern Arizona are great.