I agree that this is a good idea. We found the admitted student days helpful. We also toured schools after our daughters were accepted, which made it feel very real (they knew that they could go here if they wanted to). Some schools will let the student sit in on a class, which can be somewhat helpful (although I do not think that either daughter ever sat in on a bad class – I think that the universities know which classes and which professors are the good ones for perspective students to sit in on). On one tour I admired their t-shirt, so they gave me one.
Figuring out how bad the travel would be to each location might also be a good idea. However, if you have visited all three schools then you and more importantly your son has some sense of what this will be like. There is something to be said for having it possible for a parent to drop by quickly if the need comes up.
I am under the impression that Colorado State has somewhat milder winters compared to your other two options (even if Colorado has already had a snow storm this year).
If all are good schools and all are affordable, then I would leave the decision to your son. Are all equally affordable?
One daughter did have some difficulty deciding between three schools. All were affordable and all were good schools so we just tried to be helpful and leave it up to her. It did take her a while to decide. I think that she made the right decision.
This is what I was thinking also.
I agree with this also. Both overall requirements and major specific requirements should be considered.
Perhaps in the end your son should list the pros and cons of each school, think about it, then put the entire thing aside for a few days. Then go with whatever feels right.
And your son does have quite a bit of time to figure this out.
Also, congratulations! It sounds like your son is doing well.