I’ve given this a lot of thought over the years, and it’s a tough one. It's almost like asking a mom which is her favorite child. You really can’t choose. I have to admit, though, some books were easier for me than others (um, I guess that applies to kids, too, doesn't it?). I do have a certain partiality to the stories that have a compelling character whom I can't get out of my head, and to the stories where my characters get away from home.
For instance, I loved writing Phantoms Can Be Murder and Competition Can Be Murder in my Charlie Parker series. Both were inspired by trips to England and Scotland where the locations give such a sense of history. Old graveyards, huge stone castles and echoey cathedrals have always fascinated me. A memorable drive along the entire length of Loch Ness, together with tours of a couple of Scottish castles provided details for Charlie and Drake’s adventure in Scotland in Competition. Several stays in Bury St. Edmunds in Suffolk, along with a lot of reading about the variety of haunted sites in the area, provided ideas for Phantoms. Both of those books came together for me so vividly that I didn’t want them to end.
So, although I can’t really say that I have a ‘favorite’ there are definitely some that hold a singular place in my heart. I hope they are special to you, as well. Happy reading!