Just another GR refugee. Other than that, I had a stroke in 2004, and read almost anything I can get my hands on, though I have a particular weakness for history, mystery, and historical fiction.
Ian Mortimer's "Time-Traveller's Guides" to medieval or Elizabethan England are both enjoyable and informative, and both are organized like travel guides: "what to see," "what to eat," etc.
I enjoyed all of the medieval guide, but was most fascinated by the chapter "what to wear." I learned a great deal, including that this is possibly the only century in fashion history where men's styles of clothing changed more than women's. Absolutely fascinating.
The Elizabethan guide gets off to a slightly slower start, but includes interesting material on the changing nature of "aspirational" house materials for the new middle class (chimneys at the start of the reign, window glass at the end). It also features an aside I really enjoyed, that Sir Francis Drake's circumnavigation voyage was "not a pleasure cruise."
The medieval one is slightly better (I gave it 4.5 stars, compared to the Elizabethan's 4 stars), but they are both worth a read if you are interested in their respective periods. Both include very nice picture inserts, too. I should think both would be useful to historical novelists, as well.