I normally ask "is breakfast included in my room rate" when checking in. It is usually not. The receptionist then often replies that "it is not, but as you are CC Concierge we offer you complimentary breakfast anyway".

When they don't, I simply tell them that "it is my understanding that as CC Concierge...". After a short consultation with their boss it is always OK.

I have never received vouchers. The breakfast is normally charged to the room and charge removed at check out.

I normally travel alone, but have received free breakfast for both myself and partner when we have been together, also on award nights.