We like to take 70 to Glenwood for the time saving part of it and then take 133 from Carbondale over McClure Pass (8750) on 133 through Paonia to Delta and down the Western Slope. Still takes around 7 hours, still can shop in Montrose and the Crystal River valley in June is beautiful. It is also the beginning of cherry season in Paonia so always pick up some fresh fruit also. If not this time, try it sometime. It captures the huge variety of climates and landscapes here in CO.
This drive is absolutely beautiful. We did it once coming home a few years ago. Hope to do this again some year soon.
The drive on 285 to 50 is much more scenic than 70 to GJ. It can be a headache, though, if there's a lot of construction. I like cotrip.org for information on planned road work, closures, etc. Happy and safe travels.