This is just my take on this, but I'd say rank them all (that you interviewed at, obviously). Think about it. By not ranking a program you interview at, you're in effect saying you'd rather scramble or not get a spot at all than go to residency at a program you interviewed at but didn't rank.
IMHO, the time to decide on how many programs to rank is when you decide how many invitations to accept.
Of the 10 interviews I went on, I'd be happy at any of them. Obviously, I'd be happier at some than others, but even at my #10 program, I'd still be doing EM and that beats medicine anyday.
Of the 10 interviews I went on, I'd be happy at any of them. Obviously, I'd be happier at some than others, but even at my #10 program, I'd still be doing EM and that beats medicine anyday.