I recently used one of my PMUs for the first (and probably last) time to guarantee that I sit up front on the ATL-LAX flight on the 777. I was going to do something similar to try and get an upgrade for the new LAX/SFO-JFK BE service, but when I read that DL was mostly holding back upgrade space until the gate, I opted for the cheapest fare and the upgrade lottery instead.
Being purely a leisure traveler going on my own dime, I can't justify the prices for Y/B/M fare classes internationally that I can attempt to use upgrades on. If it were not for a VDB voucher, I probably would not have even flown DL for this trip.