If it's greenside number 1 objective is to get out and leave yourself a putt for your next shot. For me, a 100% power FBS Flop out of 30/40 sand will fly about 8-9yds and roll out a few more with a 64* wedge (depending on ball of course). Then figure in elevation between you and landing spot, and also between the edge of the green and the hole, add or subtract based on that and strong head/tail winds. That bunker in front of Merion #10 isn't really a pot bunker, but if I get in there and the pin is front left about 12yds away I figure a 95-100% flop with FBS is gonna get me pretty close.
Best bet is go in Practice mode and put yourself in one and hit a few mulligans to see how your clubs/ball react.
For fairway pot bunkers at St Andrews and RSG are a different story and it depends how close to the lip you are. Sometimes you can get away with maybe a 8-9 iron to try to advance it, and sometimes it's best to just take your medicine and flop out sideways and try to save par from there.