It occurred to me that practically all commercially successful writers I can think of, have a quite limited range. When you pick up one of their books, you can be pretty sure of the style, the kinds of characters, the kinds of situations and problems occurring, and so on.
One of the few exceptions which occur to me is Iain Banks. Even just the fact that he's successful both as an science fiction (and fantasy?) writer and a "mainstream" writer is very rare. But also within those, he writes very different types of books.
Can you think of some examples of writers with wide range? I'm particularly interested in such writers as were successful early enough to benefit themselves, since it is obvious that the market asserts great pressure. The great bulk of readers have quite limited taste, and if a writer were to suddenly change his style or area radically, he might lose the bulk of the followers he has accumulated over the years. (Which is surely the reason why Iain Banks write as "Iain M. Banks" when writing SF.)
But don't shy back from mentioning less bankable writers, if their books are interesting.
By the way, this has caused me to view the life of a writer in a somewhat different light, with less desire. To be pressured to write book after book after book with the same detective in the same trenchcoat, trading sarcastic blows with the same chief of police and the same journalist... sigh.
Oh, another versatile writer occurs to me: Tim Powers. Though he only writes a book every three-five years or so, so he's probably not exactly raking it in. (Albeit he told me he earned a neat sum on the rights for On Stranger Tides for use in the fourth Pirates movie, and they didn't use a line from the book.)