US 16 sounds good. We would like to see some scenery. Even thought of trying out Bear Tooth Pass as a day trip(probably not pulling the PUP). Sinks Canyon does look nice, but we were planning on getting to our destination will as little stops as possible...less setting up and tearing down. We have a full day of driving to CO, (Boyd Lake Campground in Loveland overnight) then another full day of driving up to the Tetons.
On the way back from YNP did plan to overnight at Belle Forshe (Devils Tower) before heading to Mt Rushmore/Black Hills/Badlands. Not sure where to stay there yet and how to see it all.