If you've been to Paris and have seen most of the usual sights,, here's a suggestion for a fun afternoon. It may sound corny, but the horse & carriage ride was one of the highlights of the stay. You pick up the carriage by the Eiffel Tower and for an hour plus you ride mostly back streets of Paris while sipping champagne ( do get the deluxe tour).  The trip starts at 2:30, so have lunch in the Musee De L'Homme...it's cheaper than trying to eat In the Eiffel tower, and you get a superb view from the terrace.