Creating a fictional world

When you write anything, everyone has a bit of advice on the way to do it. And of course no two bits agree. I'm definitely finding this in mysteries. Uber agent and legendary writing coach Donald Maas says every sentence, every paragraph, ever page has to vibrate with tension. Others say description slows down the activity, but then some say description creates the world in which the fictional characters operate. As I rewrite these days I'm most aware of description, because I use quite a bit of it--though, I hope, in small bits. It seems to me that Maas' advice holds true for thrillers and suspense novels--traditionally those where danger is present on every page. Often the victim (or stalkee) knows who the villain is, and it comes to a question of who can outlast who and who can trip the other one up. I recently read Mary Higgins Clark's Pretend You Don't See Her  in which the protagonist, witness to murder, is put in the federal witness protection program. She lets a trivial bit of information slip to her mother in the weekly phone call they're allowed, and the mother, interested in her daughter's welfare, buys a newspaper from the city where she now knows her daughter is, then leaves the newspaper on a chair in a restaurant. You got it--word is quickly sent to the hired assassin after her. So the reader is on pins and needles--will he get her or will she escape? (I truly don't think this much info is a spoiler.) I have always joked that I don't want to read Mary Higgins Clark when I'm home alone--well, I do, but they're scary on every page. That's the kind of tension Maas is talking about.
But I'm writing--or trying to write--cozies, a whole different kind of mystery. Cozies usually feature an amateur sleuth--in my case, a real estate agent who is drawn into solving an old murder because she finds a skeleton in a house she's renovating. Neither the protatgonist nor the reader know who the murderer is nor when someone else will fall victim, so there's your suspense (sometimes I think the author doesn't know either!). But the word cozy implies something different from the nail-biting suspense of the thriller. What draws me into the cozies I read is identifying with the protagonist--she (or he, though it's almost always a she) and the world in which she lives and the people around her become real to me, so that while I read I live in that world. And if it's a really good book, I'm reluctant to leave that world when I finish the book. In the mysteries I'm working on now, the world consists of Kelly O'Connell, her two young daughters, her boyfriend, Policemen Mike Shandy, her assistant Keisha, and the landmarks and houses of Fort Worth's Fairmount district. To make all that real to readers, I have to describe. I'm well aware however of the danger--reader boredom--that lurks in pages and pages of narrative desription. The old writer's saw, "Show, don't tell," is ever true, so it's a trick to work in description yet avoid too much narrative voice. Have I succeeded? Only a good editor will know. My mentor says I have. But it's a constant balancing act.
Readers are as different in their tastes as authors are in their creative leanings. Some prefer noir, exporing the dark underside of life; some prefer taut tension; some prefer the world of cozies--the craft group, the bakery or tea room, the flower shop, and, I hope, the real estate/renovation world. All I can do is keep writing and keep querying. I have a query out now on Skeleton in a Dead Space to Turquoise Morning Press, a small press about which I hear very good things, including that they want mysteries. And I'm working on No Neighborhood for Old Women. But soon my conscience will draw me back to a project with a more sure market: that book on chili.
A marketing note: a man named Joel Kirkpatrick has put together an anthology of first chapters of books on Smashwords or Amazon. He calls it the Bestseller Bound (BSB) anthology, and you can find it at http://www.scribd.com/jbkirkpat. The first chapter of my Mattie is in Volume Two. The anthology is a free download, and if you like the opening of Mattie's story,  you can order it, I think from Amazon or Smashwords. It's hard to publicize digital reprints, so Joel's project seems worthwhile and generous of him.