It's hard to say as every application is different. For me I've used AvalonDock in a couple of different applications, one which is very document driven, another which doesn't contain any documents at all, but where it is useful to allow users to be able to move different screens of the application around to make the most productive environment for them. They both work very well, but in different ways.
I don't know if it really answers your question, but I hope it helps in some way.