We spent two weeks in Paris last July, after three weeks in London, Venice, Barcelona and a 12 night Med Cruise. Best. Vacation. Ever. And Paris was the icing on the cake. Definitely my favourite place in the world.
I ordered DLP tickets online ahead of time and printed out the vouchers, which worked just fine. The RER ride out to the park was super easy and took us right there. We really enjoyed our day. The parks are smaller and very manageable. Not as big or exciting as WDW but honestly, our kids, after having spent weeks touring museums, galleries, ruins, etc, were just happy to play for the day. And so were we! We had a lot of fun.
I did notice the line-cutters, in some cases they were really bad. One was for Space Mountain. The line was pretty packed and we wanted to go on one last time before heading back to our apartment in Paris. There was a group of four adults (French) who just kept pushing past everyone. At first we were annoyed (Good Canadians that we are, we respected the idea of lining up) but after watching them and their grins/excitement/happiness, honestly we just laughed about it. They really truly didn't think they were doing anything wrong, they just were trying to get on the ride faster. If we let it upset us and ruin our day, that would be our fault not theirs, IMO.
Our day at Disney was really worth it, and definitely something we still talk about. We spent one day at the Harry Potter Studios in England and again that was a highlight (amongst many, since we were in Venice, Athens, Rome, Florence, Istanbul, Mykonos, Naples, etc!!)
Enjoy your cruise, enjoy Paris, and enjoy DLP.