What is the best mode of transportation from Dublin Airport to Straffan or Maynooth? Is a reservation necessary?
For Maynooth there is a direct bus service from the airport - see https://airporthopper.ie/maynooth-timetable/ here. For Straffan you would have to go from the airport into central Dublin and get Bus Eireann route 120 which is every half hour on Mondays to Fridays, hourly on Saturdays, and two-hourly on Sundays. See http://www.buseireann.ie. Advance reservations are possible on both services but I don't know how vital they are.