In Paris now. Had no idea it would be so crowded, and didn't buy tickets ahead of time. Louvre is fully booked the rest of the week (May 1 holiday doesn't help). I can't imagine leaving here without visiting. What are my options?
Just go early and get in line. I had totally forgotten to book the tickets to the Louvre ahead of time, so we decided to try for a ticket anyway (this was a few weeks ago on a Monday). The museum opens at 9 am on Monday, so we got to the Pyramid entrance probably around 8:40-8:45 am. There is a line that is specifically for people without reservations.
We joined that line, which probably had around 40+ people in it then, and just waited. Shortly after 9am, the line started moving, and by 9:15 or 9:20am, we were inside the Pyramid buying our tickets from the wall kiosks. It was very easy and I was impressed with how quickly the line moved.
FWIW, I did notice that the line was MUCH MUCH longer when we left around noon, so definitely get there as early as you can. Also, because it is probably busier now than it was in early April, I would suggest getting there even earlier if you really want to get in.
You can still stand in line at the Louvre if you do not have tickets but the lines can be very long and move at a snail's pace.
Let us know how things work out for you. There's been a discussion on another thread about whether one can use the Amis du Louvre (Friends of the Louvre) card to get in when the website says the museum is booked up, so it would be good to know what you find out about getting a walk up ticket.
There is a new book out called Adventures in the Louvre by Elaine Sciolino, a retired NYT journalist. She has a piece in there on "how to visit the Louvre on a Tuesday when it's closed", lol. It involves seeing the outside of the building and then doing some other things nearby. I actually was so enamored of the book that I wound up buying the Kindle version after I'd checked the hardback out of the library and finished it. It was under $10 on Kindle the other day so that might be a possibility for you. It does not get you in to see the big 3 - Mona Lisa, Winged Victory of Samothrace and Venus de Milo - but can give you a flavor of the building.
Depending on what you thought you might want to see at the Louvre, you might sub in the Cluny Museum of the Middle Ages. If you wanted Rembrandts there are some in the smaller collections such as the Cognacq-Jay (also has some nice Canaletto's) and there might be a Rembrandt at the Jacquemart-Andre.