The Showboat is at one end of the boardwalk, the Hilton is at the other end. It is probably a 4 mile walk from one end to the other. Parking is not free in Atlantic City casinos. It would not be worth anyone's while to do this for you, it would probably take 3 hours or so to visit all the casinos and cash them in. You might be in luck if you happen to team up with a local is going to trade in their own chips. Your best bet might be a below face value offer. The Trump Castle is no longer open, it was replaced with the Trump Marina. They should take the Trump Castle chip at the Marina, but it might take a little effort to make it happen.