I did cards. I bought the boxes of 100 that you can get at Target or Walmart, not expensive at all. I sent them to all but one school I interviewed at. I had one school that didn't accept me, that I sent cards to; had another that didn't accept me, that I didn't send cards to; and three that accepted, that I sent cards to. Some people say that cards are kept in your file. Others say it doesn't make a difference in the world. Do it if you feel nice. But if you don't, don't sweat it. And email vs card vs note is no biggie either.
I don't think it matters. The only school to which I sent a thank-you note was the only school that I did NOT get accepted to. Again, I don't think they really care one way or the other.
