I really liked The Historian and still have vivid mental images from it because of Kostova's descriptions. I liked her book The Swan Thieves even better. Other books I've read and enjoyed so far this year are:
The Invention of Wings by Sue Monk Kidd - a novel based on the life of abolitionist and feminist Sarah Grimke
The Madonnas of Leningrad by Debra Dean - an old woman suffering from memory loss remembers saving the art at the Hermitage and her life during the siege of Leningrad
Gentleman Jole and the Red Queen by Lois McMaster Bujold - the next installment in my favorite Miles Vorkosigan sci-fi series, this one from his mother's point of view
The Invisible Ones by Stef Penney - a private investigator is hired to solve the mystery of the disappearance of a gypsy woman 6 years ago; a surprising twist at the end
A Slip of the Keyboard: Reflections on Life, Death and Hats by Terry Pratchett - a collection of his non-fiction articles, essays and speeches with more recent comments explaining each one; a must for anyone who loves his fiction