Since I live in Colorado I'd have to say that there isn't much problem with the altitude other than what another driver mentioned regarding putting things in ziploc bags. It will make things spill open at certain elevations.
For the most part, I'd say driving out west is a lot more "reasonable than driving with a zillion 4 wheelers in the east." I realize I'm partial to the west. But don't assume that I've been here all my life. I've lived in 12 states and in each part of the country other than the north west. So I'm not a Native Coloradoan! I know what I like and don't for climate etc...
The problem you'll face out west in the winter is the lovely chain season. Most people park and wait for the passes to open. Although, that didn't work for me last year. I was on the top of Donner after sitting 6 hours as it snowed to beat the band. I was told by CHP in no uncertain terms that I would chain.
They've already had to chain over Vail this year. One of my friends who drives strictly between Denver and L.A. told me that if you hit Vail and Eisenhower between noon and 2 you usually won't have to chain. It's worked for me but I'm sure sometime along it will be snowing and it won't work well... UM...
Good luck and enjoy yourself while driving out here. Remember it 's best to hit the passes in daylight when it's not snowing. Otherwise, you'll stand a good chance of having to chain.
One day this past spring, north of Weed, CA, there must have been 200+ trucks going over the passes on I-5. It looked like a train there were so many trucks. It had been shut down all night. That was interesting to see all those trucks at one time heading over the pass.
8) :roll: