we just got back from 3 days in Paris and 3 days in DLRP...
We also go to WDW every year and this is our second visit to DLRP in six months..
We had a good time in Paris.. but DLRP was So much more fun! we did all the usual touristy paris things... DS7 wasnt into the shopping etc.. but we did the eiffel tower, bateau mouche, open top bus...notre dame.. and the not to be missed cineaqua aquarium...
but then.. we were scrabbling around for things to keep DS7 busy and occupied. He is not yet into museums.. so we couldnt WAIT to get away from the culture (we have done Paris as a couple, many many times before!).. and get into some serious consumerism at Disney!
You need much more than one day at DLRP.. as virtually NOTHING is the same! The rides might seem the same but in many cases they are new and improved - so dont be fooled that Buzz Lightyear is the same ride... or Space Mountain.. plus there are many attractions not to be found at WDW..
also.. the queues tend to be a bit longer than at WDW.. not due to the amount of guests but more about efficiency of getting people on and off rides etc.
For us..had we had our time again, whilst we were glad we did the paris thing.. we just needed one night in paris and the rest in DLRP.. we couldnt wait to get down there!
It may be that you know paris very well and have lots and lots of things you want to do with the kids.. but we struggled a little with him.. particularly with the language barrier.
Good luck!