For friends traveling to Paris for the first time, my advice is, if you are only visiting the Louvre to see the Mona Lisa and Winged Victory.......skip it. This is all you'll see of Mona, a sea of tourists with iPhones taking photos. Thanks to my travel amie Mary Gilbert for lending this photo to illustrate my point.
UPDATE: Thank you dear reader Vreni for pointing out that on Wednesday and Friday evenings, the Louvre is open till 10 p.m. and is not crowded. I also hear from friends that they offer docent led tours in the evenings that just hit the high spots of the museum which is a good use of time spent there.