Most of the following novels were mentioned as being set in "the long eighteenth century" during a discussion in the winter of 2000/01 on the Eighteenth Century email list (C18-L). If you want to see whether anything more was said about any of them, you can go to the list archives and do a search on the author or title. I've included publication information where it was given.
This list was originally compiled in December of 2000. Some items were added in the spring of 2006, and a few more since then.
There was a similar list, compiled in October of 1999, and -- as of March 2006 -- not updated since, on the Canadian Society for Eighteenth-Century Studies site. It has apparently moved; if you know where it now lives, email me and I'll re-link it here.
Ackroyd, Peter, Chatterton, New York, Ballantine, 1989 (1987).
Ackroyd, Peter, Hawksmoor, New York, Harper & Row/Perennial, 1987
Adahazzi, Federico, The Merciful Women, Londres, Doubleday, 2000
Alexander, Bruce, Death of a Colonial.
Assiniwi, Bernard, The Beothuk Saga, Toronto, McClelland & Stewart,
Bainbridge, Beryl, According to Queeney, Carroll & Graf, 2001.
Baruth, Philip, The Brothers Boswell, Soho Press, 2009.
Bosse, Malcolm, The Vast Memory of Love, NY: Ticknor & Fields, 1992
Bradbury, Malcolm, To the Hermitage, Londres, Picador, 2000
Brooks, Geraldine, Year of Wonders, Penguin.
Brooks, Peter, World Elsewhere, New York, Simon & Schuster, 1999.
Brown, Molly, Invitation to a Funeral.
Byrd, Max, Jefferson : A Novel, New York, Bantam Hardcover, 1993
Calvino, Italo, The Baron in the Trees.
Coetzee, J. M., Foe, New York, Viking Penguin, 1988 (1986),
Colegate, Isabel, The Summer of the Royal Visit.
Cornwell, Bernard, Sharpe's Triumph, Perennial, 2000.
Crumey, Andrew, D'Alembert's Principle : A Novel in Three Panels, New York, Picador USA, 1998, 208 p.
Crumey, Andrew, Pfitz, New York, Picador USA, 1997, 176 p.
Donaghue, Emma, Slammerkin, H.B. Fenn.
Ducornet, Rikki, The Fan-Maker's Inquisition, New York, Holt, 2000.
Fitzgerald, Penelope, The Blue Flower.
Flanagan, Thomas, The Year of the French.
Fleming, James, The Temple of Optimism, Cape, 2000, 320 p.
Fowles, John, A Maggot, Little, Brown.
Gerstein, Mordecai, Victor : A Novel Based on the Life of the Savage of Aveyron, Farrar, Straus & Giroux, 1998.
Graves, Robert, Sergeant Lamb of the Ninth. Proceed, Sergeant Lamb, Manchester, Carcanet, 1999
Harvey, Caroline, Parson Harding's Daughter. Pseudonyme de Joanna Trollope.
Heyer, Georgette, Bath Tangle.
Heyer, Georgette, Black Sheep.
Heyer, Georgette, Friday's Child.
Heyer, Georgette, Lady of Quality.
Isabel Colegate, The Summer of the Royal Visit,
Jolis, Alan, Love and Terror, Atlantic Monthly Press, 1998,
Keneally, Thomas, The Playmaker, New York, Harper & Row, 1988 (1987).
King, Ross, Domino.
King, Ross, Ex-Libris, New York, Walker & Co., 2001.
Kurzweil, Allen, A Case of Curiosities, New York, Harcourt Brace Jovanovich, 1992, 358 p.
Liss, David. A Conspiracy of Paper. Ballantine.2000
Mantel, Hilary, The Giant O'Brien, MacMillan / Fourth Estate, 1998
Maraini, Dacia, The Silent Duchess, New York, Feminist Press at The City University of New York, 1998
Miller, Andrew, Ingenious Pain, 1997.
Mount, Ferdinand, Jem (And Sam), Carroll & Graf, 1999 (1998),
Mukherjee, Bharati, The Holder of the World, New York, Fawcett Columbine, 1993
O'Brian, Patrick, Master and Commander.
Pears, Iain, An Instance of the Fingerpost, New York, Riverhead Books, 1998
Prast, Gila, Ossian
Schine, Cathleen, Rameau's Niece, New York, Ticknor & Fields, 1993
Settle, Mary Lee, I, Roger Williams, New York, Norton, 2001.
Sherwood, Frances, Vindication, New York, Farrar, Straus & Giroux, 1993.
Sontag, Susan, The Volcano Lover : A Romance, New York, Farrar Straus Giroux, 1992.
Steffler, John, The Afterlife of George Cartwright, New York, Henry Holt, 1993 (1992), 304 p.
Tremain, Rose, Restoration : A Novel of Seventeenth-Century England, New York, Viking Penguin, 1990
Unsworth, Barry, Sacred Hunger, New York, Doubleday, 1992.
Wharton, Thomas, Salamander, Toronto, Maclellan & Stewart, 2001
Winterson, Jeanette, Sexing the Cherry, New York, Vintage International, Vintage Books, 1991
Winterson, Jeanette, The Passion, New York, Vintage, 1989 (1987).