I had fun watching yesterday the movie version of one of Crichton's latest opus: Timeline. Although I would never have picked up a Crichton book, Jean-Pascal Tranié (formerly head of Viventures, with Edenworld now) - a history fan himself - convinced me to pick up the book last year.
The story is set in the 14th century, in the midst of the 100-year war between the French and the English. Add in a bit of futurology such as teleportation, a little romance between 2 couples, some historical details, and a thriller plot, and you get a pretty entertaining book for the beach. The movie falls short of the good experience of the book: the bad guy's character in the book is described as some kind of egotistic tech wünderkid, whereas the movie doesn't really explain it: the team travelling back in time is actually a bunch of historians : in the book they display amazement after amazement when they compare real-life with their theoritical hypothesis. It only happens once in the movie.
Nevertheless, if you fancy medieval age stories, (and the movie shows some nice medieval set and costumes), check also A knight's tale: you will see a lot about armoury and tournaments, which brings to life the real stuff you might see at the Metropolitan Museum in NYC or at the Wallace Collection in London.