My wife and I are planning a trip to London and Paris this Fall/Winter. Anyone have any tips about the best way to book (and get a good deal) for a multi-stop trip? We plan on going from Sacramento (or San Francisco - which ever is cheaprer) to London, then we'd like to go across by train (unless anyone knows other scenic/fun ways) to Paris, then fly back from Paris. We would like to fly either business or first class. Any tips?