We go to Paris once in a while with the family. As far as hotels go, we have pretty good luck just using the standard hotel booking sites: hotels.com, trivalgo, bookings.com, etc. I don't know how many you have in your family, but keep in mind that hotel rooms tend to be small and many hotels don't have rooms for families. Sometimes it requires getting two hotel rooms or renting an apartment through VRBO or similar.

Second the suggestion on the bikes. We have used Fat Tire bike tours in the past (ranked highly on Trip Advisor) and enjoyed their guided tours very much. If you get the day and night tour package (which includes an evening boat tour on the Seine) you get a pretty good discount. Kids love riding the bikes in a big guided tour gaggle down the Paris streets.

We also have done the Sandeman "free" walking tours in Paris, also highly rated on tripadvisor.com. They're free, but you're supposed to give a tip at the end based upon how well you enjoyed the tour. I have yet to receive anything less than very good tours from them.

The first time I went to Paris, I did the double decker bus tour, but I don't recall which one. Regardless, as lame as I thought they would be, they were a great way to get a lay of the city, allowing us to see sites that looked interesting, then visiting them later on either by walking and/or using the Metro.

Paris is expensive, despite the favorable exchange rate we are currently enjoying. Hotels in Paris commonly include a light breakfast, so you're covered there. We like to go to the many bakeries and get sandwiches and drinks and just eat in the many parks, which saves quite a bit of money for lunch. Restaurants in particular can be quite expensive- 5 euro cokes and 15 euro cheeseburgers are not uncommon. As mentioned above, the Latin district has tons of restaurants in direct competition with each other, so the prices there tend to be more reasonable. Otherwise, try to find places to eat AWAY from the super-touristy areas so you don't get gouged.

Note that in Paris the RER C branch is mostly closed downtown due to construction. It is kind of a PITA when trying to get around as it runs down the middle of Paris and for us is the "spine" of many of our Paris travels. If you want detailed instructions on how to get from Charles De Gaulle to downtown using the RER and getting around on the Paris Metro (subway), drop me a PM and I'll send you my notes.

Have fun. It's a great city.