I'm planning to buy some airline tickets that are fully refundable for cash, though purchasing Southwest tix is also a good option if you can use them in the next year or so.

Since WebMiles converted to the fixed price redemption rules, you really can't do better than taking the cash. Find a fully refundable ticket on Orbitz that costs more than you have coming (to get all you money out of WebMiles), then turn the tickets in to the airline after you receive the ticket.