For those who aren't familiar with this drive, here it is....
Interstate 70 West (Denver going towards the mountains)
Interstate 70 East (The mountain towns coming into Denver)
If you take an established girlfriend from Denver International Airport to the mountain towns on Interstate 70 West, you'll impress her a lot if she's never been.
Breckenridge is good for people who are doing 1-2 week ski trips or summer trips. All the Colorado mountain towns are good for that. A man will impress his girlfriend/wife if he takes her to Breckenridge for 1-2 weeks either in winter or summer.
A man will impress his girlfriend/wife if he takes her to Aspen, Vail, or Beaver Creek for 1-2 weeks either in winter or summer.
I'd rather do a Colorado mountain town trip as a childless couple than as a married man with a family or as an unattached, unaccompanied guy in either winter or summer.
People from the Dallas area are well known for going to the Colorado mountain towns in the summer.