There's a lot of information available online for historical settings, too - maps and old postcards and tidbits gleaned from genealogical research and so forth. We have it so easy! And yes, especially for present-day settings being able to listen to locals is a boon, but then again I'd never write a novel set in the present day in a place I hadn't stayed in for a good long while. For historical fiction, you have the same problem of modern day conversations distracting from what people in the past would have been interested in. Even accents and vocabulary change over the years.

And that is a great compliment from Mr. P! I try to stay away from explaining time machines as much as reasonably possible. :)