Oh, and "Well, she was old/lived a long time/something of that nature" when an older person dies. As if we're not allowed to grieve if the person is beyond a certain age when they die.
Excuse me, but I miss my grandparents terribly. I don't care if one of them WAS 96 when he died - does that change the fact that I had 30-something years with him - loving him and knowing him? I didn't want to hear that it was time for him to go.
In addition to that is telling the grandchildren that they're not allowed to feel grief "like the real children of the person does."