My wife and I both have the Amex Hilton which has the $50 Hilton credit every quarter. We used a free night to stay in the Tel Aviv Hilton on April 1st and ate at the restaurant there that night. We received the credit with no problem. We split the charge between the cards so received it on both.
I bought a gift card to the spa over the phone on March 30th, and split it between the 2 cards. It did not trigger the credit. They said that though it is the official spa inside the Hilton hotel, it is run by a 3rd party, so the charge was not issued. I complained via chat and was denied. I asked to speak to a supervisor and and he manually approved the credits.
But it's good to know that the Waldorf is an option. I guess the spa there is not run by a 3rd party.