My personal strategy is to unobtrusively ask whenever I can. I usually ask them over the phone if they can notate the PNR, then ask at check-in if anything can be done regarding that note, followed by a quick request to the lounge attendant, and finally leave the lounge a bit early to ask the gate agents. I've seen the most success when the check-in staff comes over to the gate area to assist with boarding, as they usually recognize the familiar face and call me over to let me know, good or bad. Call it excessive, but it can't hurt to try, can it? It's not like I'm bothering them to give me a free-upgrade... I'm "helping" them reduce their outstanding miles bank balance! :P