I was there last September, it was very cold and very wet. Strangely, the day I saw Auschwitz was a glorious, sunny day (I wrote it up here: http://skull-bearer.livejournal.com/145905.html#cutid1)
I know what you mean about the people. I was stuck there, unable to move with the shock of seeing the place for the first time, and this little old lady totters past, opens her umbrella and walks off. She didn't notice it.

When I went to Sachenhausen, I saw a lot of schoolkids laughing at the exibits and thowing rubbish. It was disgusting.