We usually stop at the Amarillo DOT travel center, on I40, it is a nice place to over night and then take the 335 loop around to US87 to Dumas, Hartley, Dalhart, Texline, Clayton... all the way to I25.
We went through Channing, coming home one time, I did not care for it.
We have not taken 69 north, from I 25 to get to 50, but have taken 50 all the way from Montrose east to I25 @ Pueblo and it is very scenic. Just keep on 50 from Montrose to get to Grand junction.
If you want to go I40 to Albuquerque and then north on I25 to 550, it is a bit further but the road through Durango, Silverton & Ouray to Montrose is spectacular. They don't call it the million dollar highway for nothing
We love camping in Colorado and try to go once a year, but, next year we are thinking of going later, maybe Sep or Oct since it has snowed on us at the end of May for the last 2 years
Enjoy your trip, come back, post pictures and tell us how it went.
-Brian