The best way to see Paris is on foot which is good news if you are travelling with a baby or a toddler (for some great walking routes click here). There are wide footpaths in the Opera district and Champs Elysees which make the use of a stroller easier. The banks of the river Seine are generally easy to manoeuvre around (however there are steps if you want to walk right on the river). However, the small narrow streets on the Latin Quarter and Montmartre can be more difficult as they can be very crowded at times and many of the streets are cobble stoned. You will also be dealing with a lot of stairs in Paris in the metro and in museums and other places of interest. Ideally you should have a sling or baby carrier and a stroller; a fold away backpack stroller is particularly useful for negotiating the metro. For tips on slings and strollers, click here.
Batobus in Paris offers a day ticket for trips on the Seine in a glass enclosed boat and is a great way to travel around the city. A ticket allows you to hop on and off at 8 different stops along the Seine, close to the major tourist attractions. This is a great option if you are travelling with a child who is walking or have a backpack stroller or baby carrier. Taking a full size stroller the Batobus may pose some difficulties as there are generally steps up to street level and the banks of the river are cobble stoned. The hop on hop off bus tour is another great option in Paris as these buses are stroller accessible and stop at all the major sights thus reducing the need for public transport.
If you will be driving in Paris or further afield, there are car rental agencies in Charles de Gaulle airport, Gare du Nord and at a number of other locations around the city. If you do decide to rent a car make sure that you pre-book an infant car seat or booster seat. Click here to compare car hire prices in Paris and to check availability of infant car seats and booster seats.