I think the real question no one asked is, can you ride 66 miles in a day? What about just 33...how do you feel after that? I would definitely take your road bike...the impact of lower pressure, nubby tires or a heavy frame will be magnified substantially over such a distance. I'm also of the mindset, "what good is a bike if you don't ride it?" A 66 mile commute is definitely road bike territory. Invest in a good lock (or two) and your road bike will be just as safe as sitting in your house...or bring it into class with you...or your school may have bike lockers for rent.