To the OP.

As a fellow attorney I know how evil the California Bar is. I would personally go to the property in question, ask to speak to the manager. Explain to him the situation, making sure that he understands that you are not being a flake but new information came to light that you were unaware of at the time.

I would also sign up for Marriott Rewards immediately if not already. Let him know how much you enjoy Marriotts. Finally, it would also help if the other hotel that you booked is in the Marriott chain. That will show that you intend to be a long term Marriott guest.

I believe that you stand a reasonable chance of being allowed to cancel the reservation.