Ok, here's a better one...
Day 1 - 1051 miles (Wahoo) or 1118 miles (Clarks)
Northglen to Lusk, WY, Jewel Cave National Park and Rapid City, SD - 407 miles
Rapid City, SD to Pipestone National Monument, MN - 397 miles
Pipestone, MN to Wahoo (247 miles) or Clarks (314 miles)
Day 2 - 505 (Wahoo) or 432 (Clarks)
Interstate back to Denver
Either night stop gives us about 1550 miles and the turning corners are obvious. I'm also partial to this route because I can get both SD and MN checked off.
Honestly, I'm game for whatever. It's all good!