Agreed with Radiology, then Path. I took a Rads elective really early in intern year. I learned a lot of important things, but had the flexibility of coming and going and working with whom I pleased. You can opt to spend a couple of hours with the MRI and body CT guys on the first day, then breast radiographers and nuc-meds on the next. Also, use that month to finish Step 3. Finishing and passing this test in month 2 of my intern year was a nice way to round out the Steps...