Most of the rotating internship programs do not offer in-person interviews. There are simply too many applicants to offer these. Residency programs, on the other hand, do offer these much more commonly.
The type of interview will depend on the program: one single interview/visit day; various dates where you can visit depending on your availability; and by invitation only. If a program only interviews a select number of applicants and you didn't get invited, you can pretty much assume they will not rank you high (if at all). This shouldn't make you drop them from your ranking list, but it's good to be aware of this.
This post has a phone / Skype interview counterpart, and should be read in conjunction. There's no reason to repeat everything in both posts.
The basics - Do's and Dont's
After the interview
Make sure to read all four posts on this VIRMP interview series!