I visited the school that I was waitlist at, as it is my top choice. I have been waiting on pins and needles in the weeks since then hoping and praying that I get in, because it was much more than my wildest dreams could have hoped. Definitely go, as you need that information when weighing it with your other choices if you do get in.
That being said, if you (and I) don't get in, it might make the crash of feelings that much worse if you loved the program even more after visit day.