Tricks to make books long

Now, a unpublished or barely published novelist is expected to write books that are 100,000 words long. However, once you're successful, you're expected to write quarter million word tomes. So, recently, I've been thinking about how to change a book from a hundred thousand words to three times that length. What I've ended up identifying are, well, they're really just two tricks authors use to make the book longer - I feel (tho' I suspect many will disagree) that these tricks add virtually nothing to the actual narrative in most cases, save to make it longer. (Some people will think that length, in a good book, is always or almost always a desirable end. If you like the writing, a long book provides more "book value" than a short book. I disagree. It's like saying that a novel is "better" than a short story. They're not. Short stories can have a precision and elegance that a novel can't, really, possess, but I think most of the people reading this agree with that, already.) I should also go on to say, like with all things artistic, presentation is everything. They can be done well, and they can be important to the story, but largely they are not, I feel. But, here are the tricks:

Multiple point of view characters. Why write a book about one person or event when you can write a book about two or three! Like I said, this is largely a trick. You're functionally writing two or more stories that only tangentially have anything to do with each other, only becoming unified somewhere down the road - often quite a bit farther down the road. The reason that this is a trick, and rarely provides for good narration is that it . . . really spoils suspense! Because you are going back and forth, you almost always know everything there is to know! It also nearly completely destroys foreshadowing - because you know. It's an easy way to make a novel longer with making less good, diminishing suspense and often making foreshadowing irrelevant.

Flashbacks. Put some terrible secret or other back story on your protagonists and you've got good chapter fodder. If you give all your POV characters elaborate back stories, you can do this again and again. This is a trick because, mostly, the audience just doesn't need to have that many details about the past event. Sure, the character might be a super-bad ass commando ninja cyborg - but going back for length origins is usually irrelevant to the plot.

Like I said, they can be done well. But I think what has largely happened is it's become simply a way to write longer books without a lot of consideration of what it does to the overall structure of the narrative. How changing POV really distorts other techniques a writer might use, like foreshadowing and suspense, and how flashbacks are often simply irrelevant to the pacing of the narrative. That both are, well, filler. Or, perhaps more accurately, both are employed as filler in a great number of cases.

Still, I'm curious what people think.