I don't know about the CO schools but I can give you some general advice! Most interviewers will ask the general questions: Why PT? Why "Insert School Name Here"? Weaknesses/Strengths? Topics in PT?
I would practice what you would answer in regards to questions like that. I know some schools give questions out of left field like "What would you bring to a potluck?" just to gauge your personality, as well. And, some schools have a group interview where you interview with 1 or 2 more students and they ask you each questions in turn. And, some even have a written portion where you have a certian amount of time to write an essay on a topic they give you...just like the GRE.
Smile, answer to the best of your ability, and don't worry about being nervous. I told the interviewer at my school that I was super nervous and he said it was okay to be, they expect you to be--it shows that you really care about it. Also, its okay to talk about yourself and brag a little. Be confident in your abilities and what you've accomplished, obviously if they are interviewing you, you are doing things right!
As far as attire is concerned, I wore a dress because I just do not feel comfortable in suits of any kind...at all...and I knew I would be fidgety the whole day if I wore one. My dress was tea-length and long-sleeved, and I was so comfortable in it (granted our interview was literally an entire day).
Sorry to be so general but I hope you can get something out of that! Good luck to you, I hope you get into every school you applied to!!! 🙂