Dinner, A Love Story, just published a fabulous list of 25 things to do in Paris with your kids. After reading over the list, I'd say most of the suggestions would be fun to do even without kids!
We visited Paris in 2004 with our boys who were 4, 6, and 8 at the time. We had the best time with them, and honestly didn't do too many "kid" activities. We went to museums, took a boat ride on the Seine, visited Versailles and rode bicycles, went to the bakery every morning for fresh baguettes and croissants, and went to see most of the major tourist attractions.
My #1 tip for traveling almost anywhere with kids is to rent an apartment instead of staying in a hotel. We did this in Paris and it was the best decision. We had a separate bedroom for the boys, a small kitchen with laundry machines, and room to stretch out and relax after a long day walking. Plus it made us feel like locals!
What are your top tips for traveling with kids?