It's about a four or five hour drive from Grand Junction to Denver (though I've known it to stretch into nearly ten hours when the traffic is particularly bad), and that's just one way. As a college student without a vehicle on-campus, heading home for the holidays means one or both of my parents will be driving out to Grand Junction, and then immediately turning around and going back to Denver with me. Not the best way to spend a weekend, in my opinion.
We've found another solution, though. The Amtrack line runs directly from Grand Junction to Denver, with only a handful of stops along the way. It's fairly cheap, there's never any traffic (though there can be delays), and I can get home without my parents having to drive out.
It does take all day, though - leaving Grand Junction at 10:30 means I'll be back in Denver around 6:30. While the seats are fairly comfortable, they aren't really 'eight hours with minimum movement' comfortable, and of course if you want to buy food on the train, the prices are a bit ridiculous.
But just pack some snacks ahead of time, put some movies on your laptop and music on your phone (don't forget the chargers!), and all-in-all, it's a pretty good way to get across the mountains.