My school instituted new fourth year required rotations this year. There's ambulatory medicine (either IM or FM); critical care (surgical or medical ICU); sub-internship (most major specialties available); and a transition to residency month in March where we'll all take the Jurisprudence exam and hang out together until Match Day. There are 5 elective months and up to 2 months off (if you don't have to finish third year stuff).
Having required rotations in the middle of trying to interview, take Step 2 CS and CK, do aways that may overlap with your school's schedule, etc. is kind of a pain, as we're limited in how much time we take off. I would say that sub-internship and critical care are very useful rotations, though, so it's a decent trade-off. The elective months vary widely in toughness, but there's definitely a "you show up, you pass" mentality among the attendings and the students. After all, they were there, too.