Two travelers in need of Travel Card/Oyster recommendations. We arrive Heathrow and will be staying in Windsor, and traveling to central London on 3 or 4 days. We then travel to Paris for two days and then back to London for one day before departing Heathrow. We have purchased two Oyster cards for zone 1 & 2. What is our best options for paying tube/train fares during our visit?
Thank you for the help.