do you think you would go if you got in? weigh the pros and cons compared to the other schools and see what your gut says. if you feel like there's a decent chance you might choose BU then go for it. otherwise, I wouldn't bother.
personally i didnt apply to BU so i dont care whether u go interview there or not. but if u really dont think u are gonna go there anways, it would be nice to offer the slot to other ppl still waiting for interviews.
i know u worked hard and u deserve the interview and all, but there are a lot of people waiting.