I know people do this, but how? Do they space interviews with one free day in between or do they do back-to-back interviews? Does it have to be in the same city then? Do people regularly fly to city A on Monday night, interview at School A on Tuesday, then fly to city B Tuesday night and interview at school B on Wednesday and fly home Wednesday night? Is that kind of thing common? I'd like to interview at 12 schools or so, but I can't make 12 diff trips throughout the semester (as I'm sure many people cannot)
Yep, I'm from California and did this multiple times during the last application cycle (including one trip where I interviewed at 3 schools in 3 different cities in 3 days -- that was fun). Going from the west coast --> east coast in particular can be brutal because you pretty much have to lose a day to traveling because of the time difference.
Some tips (some that are more obvious than others):
-I scheduled my interviews at non-rolling schools later, knowing that it wouldn't hurt me and hoping that I could get lucky and schedule another east coast interview with it later
-Don't hesitate to call and ask schools to see if they can accommodate you at a different date (yes, even if you've already scheduled a date). Some schools are more open to this than others, but it really doesn't hurt to ask (as long as you're nice about it and the school doesn't explicitly forbid this on their site).
-If you're scheduling online, sometimes schools will limit the dates you can choose and won't make the later dates available. I think it's worth calling to see if any future ones are available if you need one.
-Be proactive about "in-the-area" emails. My opinion is that the further you're traveling, the more broad "in-the-area" can be. Again, some schools are more receptive to this than others, but I don't think it hurts you (again, as long as you're nice about it)
-Keep an eye on the school specific threads to get a sense of where in the invitation process they are (is the school giving invites to people who were 'complete' two weeks ago? a month ago?). For example, if I had an invite to school X, but got the sense that my "time" was coming up soon at school Y, I would wait a few more days before scheduling my interview at school X to see if I heard back from school Y first. You could also schedule an interview at school X but hold off on buying plane tickets
-Kayak.com multi-city flight search is your friend
-For travel between a lot of the big cities on the east coast, look into taking a train or a bus instead of flying.