Similar situation coming back from PHX to DCA first weekend of Jan but without the cash. Got a call to my cell at the hotel in PHX about 3 hours before scheduled departure. The agent introduced himself as a PHX local agent and indicated that the 757 to MSP had been swapped from a 300 to a 200 -- would I be willing to fly through ATL instead, leaving 10 minutes earlier and arriving about 30 minutes earlier (as I recall).
I had the upgrade for MSP-DCA but was on the waiting list for PHX-MSP. I asked about the upgrades and the agent said he would take care of me on both flights PHX-ATL-MSP. No VDB, but I got both upgrades, arrived early, and got ORC for the extra 70 or so miles if I'd flown through MSP.

This kind of proactive work by DL agents is really smart.