If you like Elizabeth Peters' Amelia Peabody Mysteries, you may want to try
M.C. Beaton Agatha Raisin Series (feisty female sleuth, not historical fiction, humor)
Simon Brett Mrs. Pargeter Series and the Fethering Series (not historical fiction)
Amanda Cross Kate Fansler Series (female academic sleuth, feminist, humor)
Jeanne M. Dams Hilda Johansson Series (historical mystery)
Carola Dunn Daisy Dalrymple Series (set in 1920s England, quirky characters)
Kathy Lynn Emerson Lady Susanna Appleton Series (feisty herbalist sleuth, set in Elizabethan times)
Dorothy Gilman Mrs. Pollifax Series (humor, historical)
Laurie R. King Mary Russell Series (feisty female sleuth, historical)
Robin Paige Lord Charles/Kate Sheridan Series (late-Victorian setting)
Anne Perry Thomas and Charlotte Pitt Series (historical)
Elliott Roosevelt Eleanor Roosevelt Series (former First Lady Eleanor Roosevelt as sleuth)