Collins Publishers Inc. has hit the marketing mother lode.

The San Francisco company this year published "Christmas in America," a coffee-table picture book that chronicles the holiday season from Thanksgiving to the Epiphany.But it is more than a mere book. "Christmas in America" has grown into a multimillion-dollar promotional extravaganza between Collins and K mart Corp.

All of K mart's holiday advertising - television, print and in-store promotions, $200 million worth in all - will center on the Collins book. Whether looking for tree lights or blue-light specials, millions of K mart shoppers will bear witness to this prodigious campaign.

"We're fairly positive nothing on this scale has been done before," said David Cohen, Collins' president. "We expect it to be a very good year."

Indeed, the consensus among Cohen's competitors is that Christmas would have to be canceled or 2,100 K marts mysteriously closed for his $35 book not to be a blazing success. The company expects 500,000 copies to be sold.

The story is different, however, for other book publishers. About $2 billion worth of general-interest fiction and non-fiction books will be sold this year, but most publishers and booksellers are cautious - optimistic, but not overly so - in their holiday sales projections.

The Christmas book-selling season got off to a relatively slow start in October, analysts said, because retail sales of all goods are below last year's levels. As well, there is no single book or group of books - no 1987 hits such as Danielle Steele's "Kaleidoscope" or Stephen King's "The Tommyknockers" - that seems destined to knock the socks off the book-reading public.

"We're bullish on Christmas, but we think the sales will come from different items this year," said Dara Tyson, a spokeswoman for Waldenbooks Co. Inc. in Stamford, Conn. "We expect sales to be spread across a wider range of books."

Of course, that is not so bad for the booksellers, which unlike publishers have no particular stake in one book over the next. Waldenbooks, B. Dalton Bookseller and The Bookstop Inc. expect Christmas sales to be at least 10 percent above last year's. (Each also expects brisk sales in non-book items like engagement calendars.)

The broader range of sales is fine for publishers, too. In fact, it may even be preferred to having a single blockbuster that makes - or breaks - the season.

"A wider breadth of best sellers is something everyone shoots for," said Jim Milliot, assistant vice president of BP Report, a publishing-industry newsletter in White Plains, N.Y. "But more often than not, it is usually one blockbuster that carries the list."

If publishers and booksellers "do 10 percent above last year, that will be good, not great, but good. It's just the nature of the list this year."

Lacking one of Steele's potboilers or another from King's house of horrors - "Kaliedoscope" and "Tommyknockers" each sold more than 1 million copies last year - the better-selling books this year may see sales volumes of 100,000 to 250,000 copies.

Given that yardstick, the books likely to make a decent showing include Anne Rice's "Queen of the Damned," third in her Vampire Chronicles; and Sydney Sheldon's "Sands of Time," a romantic adventure that takes place in Spain.

Alfred A. Knopf Publishers expects its "Queen of the Damned," as well as Anne Tyler's "Breathing Lessons" and Barbara W. Tuchman's "The First Salute," to sell relatively well. Yet none of the three is likely to hit the level of sales of last year's "Thriving on Chaos," a Tom Peters management book that by this time was well on its way to 400,000-plus and the coveted status of megaseller.

"The reports so far have been that sales are a little soft," said Ron Smith, Knopf's marketing manager. "There's been some uneasiness in the market."

Some book buyers, Smith speculated, may have been uneasy about the national election and waited for it to end before beginning their Christmas shopping. Most publishers assume that sales will pick up in this post-Thanksgiving period. At least, they hope that is the case; typically, 30 percent to 40 percent of a publisher's business in done the fourth quarter.

Even in the best of circumstances, though, trade-book publishing is not as profitable as other types. Trade books on average operate on profit margins of about 13 percent, while the margins for textbooks and scientific journals are between 16 percent and 18 percent.

Part of the reason is that a successful trade book typically has its genesis with a successful author. And that means heady advances and royalties. Donald Regan, for instance, received a $1 million advance from Harcourt Brace Jovanovich Inc. for his kiss-and-tell tome, "For the Record." Novelists such as James Michener can command equal sums.

Further, the trade publishers such as Prentice Hall, Houghton Mifflin Co. and William Morrow & Co. never really know how well they will do until the "returns" are in. Unlike most other retailers who are stuck with their wholesale purchases, book stores return to publishers volumes that they cannot sell. At the end of the season, a publisher may find that a fourth to a third of the 200,000 books shipped have found their way back to the warehouse.

"Trade publishing is the weakest of the weak. It's boom or bust," said Ivan Obolensky, who follows the book-publishing industry for the brokerage Josephthal & Co. in New York. "You fly blind, because nobody knows what the returns are going to be."

In an industry filled with unknowns, about the only certain thing is that the coffee-table genre is always a healthy seller at Christmas. The so-called "gift" books have been riding a crest of popularity for the past three years, Tyson of Waldenbooks said, in part because of William Collins Publishers.

Before "Christmas in America," William Collins published a series of "day in the life," books, including last year's "A Day in the Life of the Soviet Union" and "A Day in the Life of America."