How busy are the museums/monuments in Paris in month of May?

The most famous are swamped, just like in June, July, and August. Expect large tour groups from around the world. There are still dozens and dozens of other museums to visit and streets to stroll. The National Modern Art Museum at the Pompidou never has the crowds you'll find at the Orsay, nor does the Cluny medieval museum. These both have incredible collections.

If you book a behind the scenes tour at Versaille on the Versaille website, it will help you skip the lines and be able to stroll on your own after the tour.

The popular places will be busy in May.
You should consider buying the Paris Museum Pass, but see Rick's guidebook Paris for the details on how you decide if it's going to save you money.
Versailles is going to be crowded no matter what you do--but it's a gotta see (once) kind of place.

I have not been yet--I'll also be in Paris in late May--but based on what I have read, the Marmottan Museum (great Impressionist collection, especially Monet) is supposed to be less crowded than most.

Bets - thanks for the guided tour idea. unfortunately, the guided tours are sold out for my specific dates.

If I opt to visit the gardens first, would I still need to wait in line for security check?

Thanks!

Joel,
Of course the greatest Impressionist collection in the world is at the Orsay.
The Marmottan, which you mention, has "Impression: Sunrise", which started it all (arguably); although the Marmottan isn't covered by the Paris Museum Pass.

If you choose to visit the gardens first.. yes.. you will still have to wait in line for security. The gardens are free anyways.. so you will still have to wait and show a ticket to get in.. hopefully a ticket or pass you already have.. as the line for tickets is separate.. and you will wait in it for a ticket.. then wait in line for security.

For Versailles.. go in the morning BEFORE IT OPENS and get in security line with ticket or pass in hand. At least 30 minutes before. You will get in on first wave before the palace is a smarm of heaving bodies.

Alternately , you could try waiting till about 3 or so in afternoon.. crowds and lines may thin a little by then.. no guarantees though..

Versailles is not for the faint hearted.

As mentioned, the Marmottan Museum is a good tip also the newly reopened Musée Picasso Paris is it worth to visit. For both museums applies, it is best to be there when the museum opens.

After a lifetime of summer travel, in the 10 years since we retired from teaching (YAY!) we have traveled to many countries in September and May. We have yet to wander alone down a deserted street. We have been to Paris in May twice, and both times can only wonder if this is May, what must it be like in Summer?!? However, I am at peace with the idea that millions of tourists just like me want to see the most beautiful city in the world, just like I do. We are going this August, because that's when the nephew can go. We will jostle our way through the museums, happily join a stampede at Versailles, and impersonate sardines on the Metro. I would plan on doing everything you want to and possibly can. Having visited several times already, you are lucky to have the luxury of skipping anything that appears overwhelming. We're hoping to include Pierre Lachaise cemetery this time, somewhere we've not yet been. We have had wonderful weather during May, gardens are beautiful and lush, and may provide respite and beauty in one great stop. I love the Cluny (The Lady and the Unicorn tapestries especially) and have never seen crowds there. Good place to grab the pass if you choose to get it, again because of the small number of visitors as compared to other sights.The Rodin Museum is another favorite, rarely packed, and also has lovely gardens to duck in and out of. The lack of oppressive heat helps alleviate the icks all the way around and my invigorate you for any scrums you might encounter. I bet you'll have the time of your lives. Safe and happy travels!

Marmottan, Cluny, Pompidou, Carnavalet, Orangerie are all less crowded, mostly smaller, yet absolutely sensational. The Basilica of St Denis and the Chateau of Vincennes are both delightful short excursions (by metro) from the centre.

Denny,

Thanks for sharing your thoughts! Btw, I'm glad Pere Lachaise made it to your itinerary. I feel fortunate have stumbled upon the most artistic open air museum during my 2nd trip to Paris. I must say it was one of the most fascinating places I have ever been. It was Heloise/Abelard's story that prompted me to visit the cemetery. It's their intricate tomb and the epitaph as well as many many others that lured me back. Interesting enough, I never felt uncomfortable walking through the rows of graves.

I did skipped the cemetery last time I visited in Sep 2013. It was an unseasonably cold/wet fall and I didn't think I'd enjoy it as much when I had a hard time keeping myself warm. That's also why I'm very excited about my upcoming trip in May. I can't wait to visit the cemetery. For those who believe in reincarnation, you might just be walking by your own grave (of yourself in the previous life) at Pere Lachaise.....

If you decide not to get the Museum Pass, you can still get advance tickets (either at FNAC or on the museum websites). And if you don't get the Pass, a great thing to do is see the places it doesn't cover anyway, such as the Marmottan and the Jacquemart-André. Then there's my quirky fave, the Museum of Counterfeits. They not only have fake purses and the like, but also more sinister things, like fake car parts and medicines that have caused fatalities. It's only four rooms and can be seen in a short time. As a bonus, it's near the Porte Dauphine metro station, one of the few that has an intact glass canopy.

qp...Thanks for your post. Pierre Lachaise had been on the itinerary a few times but we never made it. Now, we certainly will not miss it. After reading your post, I sit and recall one of the most memorable and inspirational teachers I have ever had. It was 40+ years ago at that I took an elective course in Medieval History at Ohio State University from Dr. Pegues. It was a very difficult course, and he was the toughest and most demanding teacher I ever had. He lectured often on the Heloise and Abelard story. I might have missed it again since all I really know is Oscar Wilde and Jim Morrison, but now feel in some, odd way privileged to honor and recall the impact he had on my life. Thank you!