In Diana Gabaldon's lengthy Outlander series, she fairly quickly takes her protagonists Claire and Jamie out of Scotland where the story began. Gabaldon's characters journey over to America, and I suspect that's because this is where she is from and presumably feels most at ease. I'm from Scotland, and so my stories stay there (out of about nine novels, there is only one section of one novel that doesn't take place in my native land.) It belongs to my psychological make-up and so by extension to my characters'. I had moved Maggie and Fergus up to the north east of Scotland at the end of the second book, but they asked to come back to Dunadd for the finale. So, how could I stop them? That is where I feel most at ease.
Right now my protagonists are in a boat on their way down to Glasgow (or as it was and is in the Gaelic, Glaschu) to a monastery to beg dispensation for a couple of characters that have fallen into the hands of adverseries down south in London (or as it was known then, Londonwic.) So it was off to that great research institute, Google, to find out about eighth century sailing craft, just how much technology was available at the time to build these two-masted frames of alder covered with stitched hides and sealed with grease?
(Don't underestimate how far these primitive boats could travel- in the 1970's a sailing enthusiast decided to recreate one and sailed from Ireland to Newfoundland.)
Then, I have been delving into medieval Christianity and the kinds of things that were happening in monasteries at the time, most notable of all (apart from missionary expeditions) the crafting and writing of scripts. It wasn't so easy, as the paper was vellum - sheep, calf or pig skin stretched very thin and scoured, then coated with lime. So I have been away from my manuscript, storing up on facts and figures.
Readers like these kinds of details. People like to read and learn at the same time. They like to travel, just as long as they can stay at home while they are doing it.