canceling at the very last moment seemed bad form at the time
There's all sorts of valid reasons for doing a campus visit when you have a job offer that you will likely accept, but this is not one
! Get over yourselves, applicants! Those campus visits are not like dinner party engagements; the faculty are not inviting you because they are looking forward to your company and can't think of a better way to spend hours and hours of their time! They are investing all that precious time and money for one reason only: to see if you would be suitable for the open position.
If you have decided to accept an offer elsewhere, NOT canceling is bad form. Even if you cancel on one day's notice, not only will you be saving them time and money, but it will often be possible for the SC to arrange for their next choice to come the following week.
Just to clarify re: my experience. Had the 2nd school offered I would have very
seriously considered them. I liked the location, I enjoyed the research portfolio of the dept, I enjoyed the people and the visit.
I told them of the first offer per fora advice, and because I am a pretty upfront kind of gal. It's fine that they didn't offer. I had a little "aw shucks" moment and then got over it.
My feeling was that until I accepted the (first) offer I was still a free agent. I had a smidge of wiggle room in timing, so took it.
Like I said, I'm glad I went on the interview. I would have regretted not seeing if they were a better fit for me. As it stands, I am really happy that I stayed with First school and offer.