Breast will be almost all outpatient - means no early am rounding. Your mastectomy patients generally stay only overnight, max 2 days (all insurance will pay for - but they do so well anyway, they don't need to stay both days) unless your program does a lot of free flaps, but these tend to be younger, healthy patients.
Our urology rotation was popular for med students and residents alike because of the few emergencies, lots of outpatient stuff. ENT had more trauma, and shared "face call" with Plastics, so more coming in at night. When I did it as an elective we did a lot of H&N Onc, and these patients were admitted to the unit afterwards, so more rounding, calls, etc.
Do not look at Neurosurgery, Ortho, Vascular or even Plastics for good hours (if PRS does trauma).
Colorectal can go either way - if they also take general surgery call, then it might be busy. If they're doing all elective/scheduled surgeries, it might not be too bad, but it would still be worse than the others I've mentioned above.
The hours will vary depending on program, trauma, etc.