Hwy 385,thru eastern Colorado,and the Nebraska Panhandle is a relaxing run.Head out of Chadron,Nb.,and up thru the Black hills to Sturgis. Cannnot imagine taking an interstate and missing all the great country . There are only 2 major hwys in Co. I-25,and I-70,and they both suck ***.Spent 18 years there,plenty of great routes off the beaten path.

 

You can also use highway 71, it will take you from Colorado to Kimball, NE, then up to Scottsbluff, NE until you hit Chadron, rather just west of Chadron to 385 then into the Black Hills. Not a lot of great scenery but you can make pretty good time, pretty lonely highway though. Looks to me like you could get off I25 at Castle Rock and catch 71 north. Hell as long as you are headed north you are going in the right direction.

 

Alamomann I live in Colorado Springs CO and made the trip north a number of times.
Denver can be a crap-shoot.
Monday & Fridays is a defendant No-NO.
Tuesday, Wednesday & Thursday, 10-11am works best.
Saturday mornings 8am works most of the time.
Sunday mornings usually work OK. After 12 is another NO-NO.
The above is true "unless" there is an accident. Then it can block traffic up for about an hour or so.

Also, stay in the far Left lane until you get close to the I-70 interchange, then move over one lane to the Right the rest of the way thru DEN or you will find yourself heading West toward Grand Junction CO.

 

Great suggestion using highway 71 except that you might want to Exit I-25 to Hwy 24 at Colorado Springs. That will take you to Limon, then you can take Hwy 71 north from there. It will be less challenging than going to Castle Rock.

 

That makes sense, it has been quite a while since I have been down in that area.