Wongdoer and I are science fiction/fantasy fans, although he goes more for the geekathons and I prefer the blood-and-guts. Unfortunately, our genre has a big problem: the Multi-Doorstopper epic: A multi-book story where each volume weighs in at 500-800 pages, and often more. The lay reader may think "Tolkien" but The Lord of the Rings weighed in just over 1000 pages hardcover and essentially was one novel cut into three sub-novels.
The latter generation makes Tolkien's epic look like a haiku: Robert Jordan's The Wheel of Time = 11 books to date, more than 8000 pages, 1-2 more remaining until completion; George R. R. Martin's A Song of Ice and Fire = 4 books, nearly 3500 pages, 3+ more remaining; Steven Erikson's The Malazan Books of the Fallen (the best of the lot) = 5 books, more than 3000 pages, 5 books remaining although he's on a 3-book/every 4 years pace; Eric Van Lustbader's The Pearl = 3 books, more than 1800 pages, 2-3 books remaining.
I was in my first year of college when The Eye of the World, book one of The Wheel of Time, came out. I graduated 13 years ago.
I wasn't even a month into my last job when the third book of Martin's A Song of Ice and Fire was published in the UK; five years later, I'm five months into this job and book 4 just arrived on bookshelves after Martin cut the story in half just to get SOMETHING published.
It's somewhat insane -- both on the author's side and the reader's. Each of these series (plus another couple worth watching) demonstrate tremendous imagination and authorial prowess. They also suffer from authorial overindulgence: Jordan's overwriting has resulted in an epic that's about 800+ pages too long, 17 years in the making and littered with too many side projects; Martin took FIVE YEARS to semi-complete book 4; Erikson is the most fecund and potentially the most prolific of the bunch, but he too has worked on side projects whilst time marches on. And when all is said and done, NOT ONE OF THESE AUTHORS will match what Tolkien wrote.
The great tragedy is the possibility of an unfinished authorial symphony. Isaac Asimov died before completing his Foundation series -- both the prequels and the main series itself (which ends with a mild cliffhanger in the otherwise annoying Foundation and Earth). So for the sake of your legacies and your loyal, committed (or ought to be) fans, finish up with all due speed. Wongdoer's two-year old son shouldn't finish college before these Doorstoppers are produced.