Mont St. Michel or Versailles

Each of them is totally worth it. If you can only do one, I'd opt for an overnighter to Mont St. Michel. It is truly unique. Some will say Versailles is also unique and it is -- but it is similar to a lot of other places. Since this is your second trip to Paris I suspect there'll be a third and you can do Versailles at that time. Just one person's opinion.

Another vote for the overnight St. Michel. We have done both and have found St. Michel to be much more enjoyable and Versailles to be crowded to the point it is not enjoyable. The gardens are beautiful but the house itself is a cattle call....just my opinion....

Both are essential France visits. Would it help to reflect on whether you will eventually want to visit Normandy, the Loire, or Brittany in the future? We did an auto loop through those three for about two weeks one vacation.

I personally think that MSM will not be as enjoyable with the tedium of a one-overnight trip's travel. Time of year (unstated) makes a big difference, as does whether you will have a car. But some Americans seem to love long drives, anywhere.

I think Tim's point is a good one: There are lots of other interesting places to see in Normandy and Brittany. I would not go all the way to Mont St-Michel just to see that one sight. This is not a commentary on MSM and Versailles in particular, as I have not been to either one. (Don't tell the French National Tourist Office!)

What do you prefer 1200's or 1700's? For me it's 1200's so MSM. Versailles is easy from Paris, MSM is a long haul.

I went to MSM in mid September and the crowds weren't awful. By arriving mid afternoon, going up the ramparts and staying at the Abbey until later in the afternoon, I seemed to miss most of the masses.

I went to Versailles around the first of October and it wasn't bad at all - there was rain in the forecast so that may have caused a lot of people to skip it (not unlike Disneyland). It didn't actually rain.

I am not slamming MSM, but if you consider Delft, Perouges, Bruges, St. Malo, Antwerp, Rothenberg, Colmar, Prague, Carcassone, Siena, York, Cesky Krumlov, Vitre, Bamberg, Avila, Rhodes, Dubrovnik, Obidos ... maybe MSM is just "really good" instead of "unique." You could consider whether someplace closer to Paris is a better use of your time.

By that, I mean that Versailles is so easy from Paris, it doesn't require advance planning (except a weather forecast.) Going to Chantilly, Chartres, Giverny, Rouen take much less of a bite out of your Paris stay, even with planning. One question is what's important to you. For example, the gardens at Versailles are impressive and historic. But you didn't give a month of the year.

Mont St Michel is totally worth it. It is unique and in the top ten sites to see (and photograph) in France. I got amazing photos of the sunrise there. You have to be prepared to walk up miles of steep walks and stairs.

Both are worth seeing, though Normandy is worth a trip by itself. On my second trip to France, I stayed in Rouen for a night, Caen for a few nights to see Bayeux and the D-Day landing beaches and then went to Mont St. Michel, and then St. Malo, and then went back to Paris.

If it's your second trip to Paris, eating up time probably doesn't matter as much, so if you want to see Mont St. Michel, it's certainly worthwhile. Staying overnight there would be neat, since during the day, it's so crowded with tourists.