I think the surgical preliminary year at the "right program will be invaluable for the future ESIR or integrated resident. The key things that you will acquire include the rigors of a procedural/surgical field (morning rounds, preop orders, OR/procedural skills, post op orders (looking for post op complications), evening rounds and signout. Also, I would encourage some time on vascular surgery, surgical oncology, thoracic surgery, trauma surgery and ICU. All of these are high yield rotations for Interventional radiology but also for diagnostic radiology. You also want to make sure you get adequate outpatient clinic time and get to see some consults from the ER and floor.
When looking at ESIR candidates who want to do IR, many look at what they did for internship. Surgery>>IM>>>>>TY as a gauge of their true interest in interventional as well as their ability to handle the hours and lifestyle of a demanding IR training program.