Also, you may be able to find a Holocaust survivor in your area. We had one come two years ago, and he was amazing to listen to. Their stories affect you more than a movie ever could, and our residents really liked the program. These two can also be done in conjunction with one another, with the movie being shown one night and the talk the next. A few years ago, we had someone show up who didn't believe that the Holocause happened, and he challenged the speaker.
Food also helps.
We did the program on a Friday night, and had a smaller turnout than I think we would have had on a week night.