I just finished reading Loving Frank, by Nancy Horan. It is a historical novel about Frank Lloyd Wright and his relationship with Mamah Borthwick Cheney while they were both married to others. I love historical fiction (and really hated history in high school and college!), but admit, I often have to look up information when reading to verify what parts of the book may not be exactly accurate. It appears most of this book is on target, though some characters have been added to the story that did not exist in "real life."
If you are looking for a good book, check out this one. It does drag just a little in the middle, but nothing that made me want to stop reading.