Oh, this is a doozy of a question as I tend not to be wooed so much by one historical period over another, but rather by the untold story--whatever era it may be in! I suppose that answers the second part of your question. I'm led into various historical periods by the story spark.
In my first novel, THE TIME IT SNOWED IN PUERTO RICO, that was 1960s Puerto Rico debating statehood or independence.
In my second novel, THE BAKER'S DAUGHTER, that was WWII Germany from the perspective of a young German woman in tandem with contemporary El Paso's border patrol issues.
For my latest release, THE MAPMAKER'S CHILDREN, it was Sarah Brown and the Underground Railroad in 1859 juxtaposed with the same location in present-day West Virginia.
For my next book, I'm going to an entirely different location and century! I consider myself merely the story archeologist, digging up the bones and remnants, trying to piece together the past. If I find a fascinating fragment, I'd never toss it back simply because it wasn't from a particular historical period. I keep excavating and discovering. Always. That's my job-- to entertain and educate readers! Happy end-of-summer reading days to you, Susan.