We will be in Paris for 1 day in may. Arriving by Eurostar at about 10am leaving around 6pm. Should we buy tickets for hop on hop off bus ahead of time? If we buy there, do you pay with cash or can you use a debit or credit card. Can you pay when you board the bus at the Gare du Nord? Any experience with using this bus?
You should absolutely NOT buy ticket ahead of time, completely unneccesary, and saves you no time or money. You can buy it as you board the bus at ANY of their stops, including the one near Gare Du Nord.
I have used it, and found it fun, plus its nice to have the street side view of Paris from top deck( which you miss if you just use metro) , going around the traffic circle that surrounds the Arc De Triomphe is a hoot. There are four routes, one is the best,, the one that goes by ET.
You certainly have a short stay in Paris.
PS I just replied to your other post re ET ,, don't bother going up it since you are arriving later in AM,, but do stop by and see it!