The flier was included in the United Mileage Plus (premier version) statement mail.

The Orchid at Mauna Lani
1. 35% off, Room Upgrade, Daily Breakfast, "Thoughtful Extras" and Double Miles: Enjoy the pristine and peaceful setting of The Orchid at Mauna Lani at 35% off regular rates, and you'll not only receive 500 Mileage Plus bonus miles, you'll also receive a one category room upgrade, daily breakfast buffet (up to 2 per room), and a myriad of "Thoughtful Extras." ID: UA35BKUP

2. 50% off, Daily Breakfast, "Thoughtful Extras" and Double Miles: If you have a Mileage Plus Hotel Award Certificate, normally valid for two nights at 50% off regular rates, Premier members can now extended that certificate for an unlimited number of nights. Plus, you'll receive breakfast buffet daily (up to 2 per room), a selection of "Thoughtful Extras" and 500 bonus miles. ID: UA50BKFT

Ts & Cs say you have to be a Mileage Plus Premier (or above) to use the deal.

I am changing my existing reservations in August to UA50BKFT. Not to mention, this property is very good at platinum recognition