Don't conflate institutional prestige with IR quality. Of those that you mentioned, Stanford and ucsd are the ones most worth your time. That said, I know someone who did an away at Stanford and didn't even get an interview there. As well as someone who did an IR away at ucsd who didn't match IR at all. With respect to the other programs you listed, I distinctly recall a resident staring at me blankly while telling me he fell down to Brigham on his match list for IR fellowship and how even fellows there consistently struggle to get opportunities to be primary operator on the complex cases and don't finish training feeling totally competent. Likewise, if you go to mgh, your competency in vascular disease management will be non-existent. Northwestern vascular surgery has superstars like Melina Kibbe and IR has lost out on that territory completely. You should really be looking at places like UWashington (Seattle), MCW (Milwaukee), Rush, UVA, UMichigan, Yale, etc. Those that are clinically oriented and have particular expertise in vascular disease management. Go somewhere where IR takes care of patients before and after procedures, has heavy influence at multidisciplinary conferences, and is aggressive in obtaining referrals (especially from primary providers). Basically, places that most closely resemble Bapstist cardiac and vascular institute. Remember, the general consensus is a place like BCVI sets the bar on how an IR practice should operate. Some of the places you mentioned don't even touch any of the patients that bcvi are experts in treating. When you look up some of the practices I recommended, you will see IR groups that practice the way IR was meant to be practiced, like a surgical subspecialty
A bit of insight about the application process: Surgical residencies
highly value away rotators; most surgery places will take half their class from hard-working rotators over someone with a higher board score. Applicants to surgical residencies, particularly neurosurgery, perform 2-3 aways with the reasonable expectation that they'll match at one of those programs. This is
not the case in IR. As DJNYY pointed out, an away rotation isn't enough to secure an IR
interview, let alone match. Don't go into an away rotation expecting to match (or interview) at that program. Instead, look for aways with broad exposure to IR practice with well-known IR faculty. Get to know one of the faculty members while you're there and ask for their recommendation.
Plug for UW: I'm biased now since I'm going there for DR, but theirs is the only program that
strongly encourages IR applicants to do an away rotation with them. I thought this might be a generalization on their website, but if you compare it to
their DR page, it seems they only care about rotators for IR, and not for DR.
I also have some program-specific experiences:
UCSF: IR attending at UCSF recommended
against rotating here.
Stanford: IR rotation doesn't guarantee you an interview.
UW: They matched three IR integrated: One was a UW student, one did an away rotation, I don't know about the third.
Yale: Will rank-to-match IR rotators for
DR (usually). Not exactly what you want, but it's something.
UCLA: One person did an IR rotation there and ultimately matched DR there.