My wife and I are traveling to Paris and Burgundy in mid-July with our 15-month old daughter and two of our parents. We are looking for a 3-4 bedroom apartment in a nice area of Paris, probably to stay 4-5 nights there. We are scouring Airbnb but I’d love to hear any ideas of other sources, apartments, strategies, etc. Also interested in any ideas in Paris for a toddler. Also interested in Burgundy apartments or homes. I’d love to hear from anyone who has done to Burgundy with a toddler. Thanks in advance.
Flipkey has a ton of listings.
I found apartments on VRBO, both in Paris and Beaune, for my trip next month.
My colleagues, brother, and I had good success with this site for apt’s in the Marais. Welcome : Paris Autrement
In general a 3-4 BR apt is a bit of a tall order in Paris. You will find that many of the 1-2 bedroom places are already counting a sofa bed. 
Good luck (meant completely non-facetiously)
I use Just France. They have lovely, well-located apartments. We’re already booked for October, our fifth year with them.