I'm on the west coast this week and your query made me think: Which Six Flags? They are in many locations all over the USA. From NYC There are Six Flags in Mass, NY and NJ that are all less than a day's drive.
i'm not too familuar with NY and NJ as I am visiting from CA, but I've eaten, in Boro Park, at a place called Nu Cafe 47 on New Uteecht near 48th st. They have a large GF selection, even quinoa, which I rarely see in kosher places.