Well my time and money are very important, and I have found there are ways so I don't have to waste either. I consider the MP a waste of money for me. I only visit one or two musuems a day,, so I know the pass does not save me money. It could,, if I used it at least three or more times a day though ( but I am a person who enjoys spending a long time in museums, I do not just hit the well known highlights like many tourists do)
Lines at Versailles- Buy ticket online ahead of time, actually, with teens, make it really fun and do it with the Fat Tire Bike Tours, you will all enjoy that ,, and you do not have to be fit , just fun loving.
Lines at Louvre- Easy peasy to avoid by NOT using the Pyramid entrance,, one of the single most useful tips I have ever found on a forum, and its TRUE. Enter through the underground shopping mall and buy tickets from machine. I have done this at least 7 times,, always in summer, and never waited more then 10 minutes to go through security( which no pass allows you to bypass anyways)
Lines at Orsay- buy ticket for Orsay same time you buy ticket at Rodin,, it is avaiable there as a package ( look online site if you don't believe me) .
BTW,, YOu mention the Paris "pass" .. there is a Paris Visite pass and a Paris Museum Pass, most feel the PVP is not a good value and I am not completely sure which one you mean.
Have teens bring id for museums if they look "old" I was never asked for my kids, they were young enough to not look close to 18 , but if your teens are then they should bring id to get in free.