It is very difficult to exchange any currency anywhere in Long Island or cash travellers cheques. Luckily we had enough money for the length of our stay beacuse I had to wait for us to come back to New York to get some money.
It seems that local people are not used to foreign visitors in there, and I think that tourists other than Americans are very rare.
Ocean Beach Resort
Be aware that there is an Oceanside Beach Resort as well as an Ocean Beach Resort. I was booked (through Expedia) at Oceanside... but was inadvertedly taken by the taxi to Ocean... They were happy to take my money even though they hadn't received my booking. I ended up paying for both. They would have known that there was another place with such a similar name. I feel they were completely unprofessional not to suggest I was at the wrong one, and ring the other to check on my booking.