Hi, we will be visiting Paris for 2 full days and leaving early morning on the third day. Day 1 (arrival), we will need transportation from ORY airport to our airbnb and an On/Off Bus office for a day of exploring. Day 2, we will be going to Disneyland Paris. What is the best ticket(s) to purchase for transportation to those areas?
The simplest / fastest solution would be a Paris Visite pass/ticket 3-day 5-zone which will cover you from Orly airport to Paris using the OrlyVal train to Antony, then RER B to Paris / your AirBnB, bus office, Disneyland Paris, back to Orly or wherever your departure point will be.
You can buy this ticket from the OrlyVal train station ticket windows at Orly airport from a ticket sales agent who will help you. You'll keep this ticket and use it the entire 3 days and it will cover all Paris-run public transportation.
Since your trip will be limited in time, I think maximizing your enjoyment of the trip through simplicity and speed will make the Paris Visite ticket the best option for you.