Because we have children in school, we try to go away over the Easter holiday so that we don't have to pull them out of school for so many days. Two years ago we went to Italy over Easter and found Rome and Florence and Venice to be mobbed. Is it the same for Paris?
Most of the heavily touristed areas of the continent will be packed with visitors who had the same idea as you. Most tourist destinations usually experience a large upswing during any of the major holidays.
Rome is mobbed on Easter because it's the home of the Roman Catholic Church and Easter is Christianity's holiest day. Paris on Easter is not in the same category as Rome. However, there are closures in Paris on Easter, it's difficult to get into Notre Dame for Easter service (or so I'm told, I've not been to Paris on Easter). I agree with Tom. What happens in Rome on Easter is, you have a combination of the locals being on holiday and using public transportation, visiting "tourist" sights, plus the regular tourists, so wherever you go on Easter, it's going to be a crowded time. It's been said (this is a glittering generality) that Europeans take their holiday time seriously, that more "services" such as retail services, etc are closed than on a comparable holiday in the US. Example: Even on a regular Sunday, try to find a gas station open in the French countryside, away from the high speed routes.
I was just in Paris for the Easter weekend and it was a zoo. Then again, the big sites are always very busy, so I'm not sure it made that much of a difference. If that's the best time for you to travel, then do it.