I was speaking to the manager of the Holiday Inn Express here in the UK about this, as it varies for me from stay to stay.

If they pre-process the PC members that day (keys out and waiting), then no credit card authorisation is necessary as you're pre-authorised. Just grab your key and go.

If, on the other hand, they haven't pre-authorised their PC members that day, you've got to present a CC just like everyone else.