Marriott had been matching Gold this year. Just book like 4 reservations at Marriott. Call up and tell them you are thinking of switching from Hilton to Marriott and if they are willing to match status. Mention your reservations on file. Send over proof of your Hilton status. If they do, they will grant Gold right away with a target for maintaining it going forward.

I personally think Hilton have a better quarterly promo right now and actually switch from Marriott to Hilton for now.