happy to hear the family trip to europe, you'll have a great time. like kath says check out flying from vancouver canada. you can look at flights to orly. don't know your dates in the summer which is high season and more expensive. i would check skyscanner.com, kayak.com, googleflights for alerts. there may be sales for flights to europe, just keep looking everyday. when you see a price, times of arrivals and departures, too early to check in can you leave luggage or be lugging it around till place is available, how many stops and how long are layovers.
do you do it that way or the opposite way, fly to a different city first like david says, lots of options.
make sure if you use vrbo or airbnb rentals in paris there is a 13 digit number that apartment is legal. you don't want to get there and find no place to stay. look at booking.com and place filters, apartments, check what floor (if higher floor, climb stairs with luggage or a lift), A/C, euro budget, washer, terrace where to stay. check cross-pollinate.com, only-apartments.com. if you know the exact dates what city you want to be in and can book with free cancellation book it. no matter where you go it will be busy and crowded. just go with the flow and make sure you have down time to relax, sit at cafe, have a glass of vino, people watch. you don't need to follow hour by hour with plans, expect the unexpected. do book the attractions you really want to see early. any questions come, back the posters here will tell you good bad and ugly.