We will be doing the Uniworld Grand France that ends with an overnight in Paris. We've been to Paris before, many years ago, so we plan on spending the day with the overnight on board doing a few things we missed (going to the top of the Eiffel Tower, maybe a nearby neighborhood that we missed), then, on debarkation day, were thinking about adding a night or two in Montmartre. Is there enough to do/see in Montmartre for a day or two, or will we be able to do all of the strolling and window shopping we'd want (Place du Tertre, Sacre Coeur, maybe a show at Moulin Rouge) on debarkation day afternoon with just one overnight? The day after we debark is a holiday in France, so we probably won't be able to do much anywhere in Montmartre on that day (I'm guessing), except, perhaps, Sacre Coeur since it's open on holidays, so I'm contemplating adding 3 nights since 1 day will be limited by the holiday.