My family and I wanted to see the Mona Lisa along with other vast treasures at the Louvre. Here are a couple tips...
1) the lines are crazy long so purchase tickets in advance.
2) there are two key entrances to the louvre once you have tickets. The first is ground level near the pyramid and the other is underground near the retail stores near the bus parking. If one line is long try the other...we waited 15 minutes to get in while our friends waited 90 minutes in the other line. Also if both lines are long you can go nearby for food/snack come back to see if lines have finished. However, make no mistake you will wait in a line... patience is a virtue and treasured within are worth the wait however you decide.