I read the first two Persia Wolley books and the Sharyn Newmans when I was on a teenage Arthurian binge, but it takes a lot for me to like Guinevere and so i haven’t retained much of an impression of them, although I think I liked them. Parke Godwin’s Beloved Exile is Guinevere after the death of Arthur, struggling to hold the kingdom together - third in his trilogy.