Hey there, Moonrat (it feels a bit odd writing that, I have to say) [fair enough, dear reader],
That said, I have a couple of questions on length of submission. I write horror/supernatural suspense and my agent is currently shopping my first project(90,000 words).
My work-in-progress is going to check in at around 75,000 or 80,000 words maximum. I read widely in my genre and I've noticed a lot of debut novels coming in around 190-220 pages in trade paperback format. That seems pretty short to me, but I can't tell how many words that might be. I enjoyed Joe Schreiber's Eat the Dark (edited by Keith Clayton), which came in at 193 pages and had over fifty chapters.
My questions concern the nuts and bolts on something like this. Do editors acquire texts with fifty-plus three and four-page chapters? Does this affect the marketability/desirability of a project? I appreciate any insight you can offer on this topic.
So many interesting points here for me to talk about (ratty field day). Let me start with a caveat--although I have worked in genre fiction (and do work on some now), it's not my specialty. I'm going to have to skirt around your very genre-specific questions just a little.
First of all, you've noticed the trend toward shorter books in publishing--even genre publishing, which has historically been a safe haven for Tomes with a capital T. Maybe TV is ruining society and attention spans are getting shorter, maybe publishers are just trying to make their print margins work in an age of inflation (shorter books are much cheaper to produce).
Either way, I have to admit my personal taste is toward shorter books. I really like submissions between 60 and 80k words. I'm relatively open-minded, but anything shorter than 60,000 words usually proves to be a little half-baked. (This is not always true, of course, but often it just comes up short--a good novel needs cohesive structure and enough development to pull a reader in, and often this can't be accomplished in fewer than 60,000 words.) I also cringe whenever an agent tells me she's sending me a 200,000-word debut novel. I think the upper limit of my patience for books I edit--even genre books--is about 120,000 words. I like all my books to cast off under 400 pages when they are typeset (and I like pretty spacious font so my readers don't have to develop glaucoma over my titles).
My personal reading preferences aside, I also have some professional pressure to either acquire shorter books or edit books down to manageable lengths. There is the basic margin--book prices don't escalate relative to inflation, and it becomes harder and harder to make our numbers work at all on the book production end.
There's also the famous sell-in problem. National chains like shorter books. More shorter books fit on the same shelves as fewer longer books, but the shelf full of more shorter books has a much higher cumulative retail value. Bookstores buy more copies of shorter books. Therefore, a shorter book has a slightly higher chance of becoming a bestseller (quality of actual book not taken into account).
So I know this all seems very superficial, but from a commercial standpoint manuscript length is a factor.
That doesn't answer any of your questions directly; it's mostly me on a soapbox. To get back to your situation, it sounds to me like you're in a very healthy length range. In terms of format, I don't think you should worry about it. Write your book organically in the format that's working for you. Although gimmicks in formatting get old quickly, we (editors and publishers) are always looking for innovative structures. And sometimes the gimmicks really work (look at Chabon's GENTLEMEN OF THE ROAD next time you're in a bookstore--his gimmick is illustrations and artsy two-color chapter openers). I would say don't tailor your book's structure to anyone else's ideas unless that helps you write it more effectively.
Hope this helped. Let me know where I've left holes in my argument (I am blogging on a non-work day so my brain is a little non-working).