could be a decent value for an *imminent* booking but not really to stock up for next years bookings/holidays:

10% off at costco plus 2% (?) annual costco rebate for executive members plus 2% (?) credit card cash back

versus the loss of

​​- 2-5% in value credit card travel spend points/bonus
- loss of interest/dividend earnings (say, .5% per month?)
- loss of credit card trip delay / travel insurance benefits on airfare not paid via card