Have a look
here mate - its a good place to start.
Its always worth a punt showing your ID card, but don't forget to add the words 'Allied Forces', because some yanks are mince and won't have a clue what the RAF is. Maybe dropping into the mix about your tours in sandy places, may also add to the discount...... its worked for me.
You may also want to check out
Famous Fat Dave's Eating tour
You may think it may be a little pricey - but when you work out what you're getting - its actually quite good value and you get to eat in some of the best places in New York.