Carnival has a 10 1/2 hour excursion from Le Havre to Paris.  I'm hedging on the conservative side and thinking 3 hours of drive time each way, which would leave 4 1/2 hours in Paris.  I know it's not nearly enough time to see everything, but we were thinking of the train from Invalides to Champ des Mars to view the Eiffel Tower up close (not go up), then walk to the Arc de Triomphe via Av Kleber then walk the Champs Elysees back to the meeting point.     Is this doable?