Paris Musuem pass

Very easy to purchase there, you can purchase it at airport from tourist info desk, or from almost all of the museums it is taken at, but best to go to a smaller less crowded one so you don't have to wait in line.. there are many that would do, if you post where hotel is people can advise closest place.
Do not purchase ahead,, you just pay more and its one more thing to remember to pack!

Thank you so much

When we went in March, they were out at the airport. We had planned our first day to be just a decompression day after the flight, so we went exploring. We ended up buying our pass at the Musee d'Orsay that afternoon about an hour before closing. The line was non-existent at that time. Then we were ready to go the next morning. If you find yourself in that position - buying it late in the afternoon for another day was a great option. :)

Thank you for your help

I just want to reiterate that you should buy it at smaller, less crowded museums. At the musee d'Orsay you have to wait in the main line, and it can be very long. Buy it at the TI in the airport if you can. I didn't because there were about 10 people in line there. Big mistake.

For an additional fee you can order the passes via the website and have them delivered to your hotel. I did that last month and it worked out great. On previous trips I've had problems with places being out of stock on the 4 day passes: http://en.parismuseumpass.com