I heart Seneca Crane. This is not just because of his movie version, but also because of his mysterious sense of humanity and unwritten acts within the novels--why did he defy Snow? Was it only to prevent both potential victors from dying, and thus cause a cultural backlash? I don't think so because one's career and life is not usually sacrificed for a show's popularity. Crane, as gamemaker, was smart enough to lead the games and must have known what he was getting into when he let both live, especially Katniss who was seen as the greater threat. It's never really explained in the novel, and of any characters in the books I want to know more about Seneca. That makes him a very interesting character.
I'm fortunate to have the electronic version on my laptop, so for those who doubt the awesomeness of Seneca's mysterious "sentimentality," I list the following quotes:
" 'If the Head Gamemaker, Seneca Crane, had had any brains, he’d have blown you to dust right then. But he had an unfortunate sentimental streak. So here you are. Can you guess where he is?' ”
- from Snow to Katniss (Catching Fire)
"Then I step away quickly to watch the reaction on the Gamemakers’ faces as they read the name on the dummy: SENECA CRANE."
Therefore, we never get a personal description of Crane, and only have his symbolic importance as the victim and sacrifice in order for Katniss and Peeta to survive, and as the "dummy" (love the literary humor) who was supposedly hanged by Snow.