I am trying to determine the best (and not too expensive!) way for my family of 4 (2 adults/2 teenage sons) to get from CDG airport to central Paris. Not sure if since we have four people if going on shuttle service might be cheaper than the Air France bus and taxi to get to our rental flat. We also need transportation to get a rental car at Orly South so not sure which would way would be best. Can anyone lend me some advice?