I'm like RR. I didn't vote, but if I did it would have been the 3rd option
This quarter - no, wait it's over, anyway - I took classes at Gleacher Center on Wednesday nights. Besides the smaller classes, older chairs, and people coming from work a bit late, I'd say that it is the same thing. Yes, people don't "bond" that much, you won't make perhaps as many connections as in a Full Time program, but in terms of education I believe it is the same.
That said, I just can't believe how people can work and still study, seriously, I had my final today on Financial Instruments (read derivatives) it was hard, pretty hard. I remember somebody here taking a Wharton PT program who said that it was hard, and I agree, in Booth, Kellogg, Wharton and other schools at the same caliber, faculty won't give you a break because you're a PT or a Weekend student, actually I've heard from one professor that sometimes he'd expect more (because of experience in the field).
Oh, and remember that for some classes you will have group meetings. I managed this quarter to have "virtual" group meetings through skype, as everybody in my group was really busy with recruiting, but it was Applied Regression Analysis, which is pretty much math, if it were Competitive Strategy or Marketing for instance I couldn't have done so.
Is it 2.5 hours both ways or each? If it is both ways that's roughly 10 days of commuting

in your whole course.