Hi, Counterpointer—I think hesadork makes a good point: if writing about diversity doesn't speak to you now, can you imagine what your program would be like if diversity were a serious strand of the curriculum?
Additionally, I know applying to schools is a serious investment. However, the money you've spent is a sunk cost and should not play any role in whether you continue to apply to that school.
Like hesadork, I think diversity is one of the most important topics for education, not only in the USA, but in Canada, too. (Although, considering that's my area of interest, I recognize my bias). Having an international day is good start, but as a one day event, it may not have a lasting impact that promotes diversity. Here's a website I have used while working on a race and ethnicity unit—maybe you can glean a few strategies, too: http://www.eds-resources.com/edmulticult.htm
Also, here's another resource you might enjoy. It's the Freakonomics podcast, and this episode is about a program called Pathways to Education, a community-based educational program in Toronto that aims help struggling students graduate from high school: http://freakonomics.com/2014/12/04/how-to-fix-a-broken-high-schooler-in-four-easy-steps-a-new-freakonomics-radio-podcast/
Good luck!