Can anyone tell me if it is necessary to book theGrey Line tours ahead of time? Specifically the Double Decker bus tour of Manhattan that works as a 48 hour pass. I would like to be able to decide once I am actually in Manhattan which tour is best suited for our needs, but I'm worried they will be booked up, please help.
Thank you in advance.

I've never heard of these "selling out." It would sort of be like the subway selling out. To my knowledge you're not guaranteed a seat or an upstairs seat whether you buy in advance or not.

You will have no trouble getting tickets. If you are within a block of one of their stops, you will be approached several times and asked to buy a ticket. We did not take the tour, but we were offered tickets repeatedly.

Yes, I think you should buy tickets in advance and you should also treat everyone you are travelling with to tickets also.

It is not necessary to book this tour ahead of time. I booked our tour at the hotel where we were staying in New York. We enjoyed it very much.

hey trace08, very funny, buy your own tickets, cheapskate!

If you are referring to the double decker hop on hop off bus tour the answer is NO. If you are interested in other tours they offer then purchasing a ticket in advance wouldn't hurt.

By the way it is Gray Line Tours.