mount rushmore,on 90, then south to grand canyon . . . any recommendations on , attractions along the way
My comments relate only to the route between Rushmore and the Grand Canyon.
+ At Mt. Rushmore don't miss Custer State Park with the Wildlife loop, Needles Highway and the Iron Mountain Road. For me the Park and roads are the highlight, Rushmore just happens to fit in.
+ You will pass right by the Rocky Mountain National Park (Loveland to Estes Park). I'd consider at least a brief visit there.
+ From Estes Park there is the Peak to Peak Highway that will allow you to drive through the Arkansas Valley (Leadville, Buena Vista, Salida) my favorite part of Colorado. It should be delightfully cool.
+ I'd go on down to US 160 and across to Durango (won't add many miles if any to your overall route.) From Durango you can make a stop at Mesa Verde--and the possibility of taking a breathtaking train trip up to Silverton.
I hesitate to give precise road directions because the directions will be far more complicated than the actual driving, but I will just give the highway numbers. South Dakota 79 to US 18/85 to I-25 South. If you go to Estes Park: US 34 from Loveland. The Peak to Peak highway is Co. 7 to Co. 72 to Co 119 to I-70 West.
From I-70 South on Co. 91 to US 24 at Leadville; then US 285 down to Co. 12 over to US 160 West. That will take you all the way to Durango and Mesa Verde.
Look on any good map and you will see that this is a pretty direct route from Mount Rushmore on toward the Grand Canyon.