Travel agents can still hold reservations without ticketing (subject to ticketing rules of the fare held). But you'd likely need to talk to a person, and I'm not sure if OTAs like Expedia would do this (they'd probably charge a nonrefundable phone booking fee anyway).
The other option is a mileage award ticket which (as long as you're originating in the US) is fully refundable and you won't have the charge on your credit card for a cash paid refundable ticket.