I asked William Arndt about the College Inn some time ago, and he responded with what I think is the correct information-I can't recall for sure, because I lost his note. But this is more or less correct: built in 1964 as a private residence hall by College Inns of America, it had a Denver architect, and was thoroughly of its time; lots of glass, and the divisions between the floors are obvious because of the cantilevered porch extensions of the floor plates.
Like other buildings of the time it was an asbestos mine, and mitigation would have been difficult. Add to that the cost of bringing the rest of the building up to code, and you can see why they decided on tearing it down.
Still, it had good lines, and unlike the recent buildings along Canyon, it was quite sleek. I was suspecting that James Hunter designed it and was surprised that it wasn't.
Please correct me on the information I provided, or send a comment if you have a story of your own about the College Inn or anything else related to architecture in Boulder, on-campus or off.