No need to go all the way back to Glenwood/I-70. Take a left at Carbondale on the way out of Aspen and take this route over McClure pass for bit shorter drive:
But, if driving at night or in a storm I'd probably take the I-70 route to Grand Junction then down 50 to Montrose. McClure Pass can be a bit sketchy.
Either way Aspen to CB is a long drive in the winter to go a short distance as the crow flies.
On the trip in general... for the best skiing, don't fall into the trap of trying to lock everything down in advance. I'd still say keep flexibility and hit 3 of the 4 mountains with the best snow, and spend extra time where you find the best conditions. But... traveling with your girlfriend you probably want to have things locked down a bit more. My wife is the same way, and wants to know details in advance. I'll lock down the first and last couple nights, then keep everything flexible between. That usually keeps up both happy.