I was fortunate to be a round-one judge in the ITW contest for best novel, etc., a while back. One of the paperbacks I received was COLD DARK MATTER by Alex Brett, a Canadian novelist. I liked the book very much, and recently having found it again, had a re-read. It held up well the second time around, and having visited the Mauna Kea observatory years ago, it brought back memories of a fun time. And a cold one. Who knew it could get freezing in Hawaii! Anyway, the mystery involved the Cold War, astrophysics, and Hawaii, all fascinating. I'm going to hold on to this pb a while longer, I do believe.
FALLING WOMAN by Pat Murphy is another book I can't excess from the shelves. Winner of the Hugo years ago, it's a fascinating time jumper (Mayan to present day), filled with a story so original, I re-read it periodically.
ARABELLA by Georgette Heyer never fails to make me lose myself in Regency England and the details of a character both classic and stunningly original. For sheer writing ability, Miss Heyer is one to study, and I always feel as if I'm a mere mortal at the feet of a writing master.
None of these three books are terribly popular, or even well-known today. But I keep them where I can find them whenever I need to read a good, well-written story with original characters. I'll add to my list later when I've had a chance to do some more re-reads.