Larp is an interactive medium. I can’t help feeling that attempts at public relations that don’t demonstrate that interactivity won’t achieve much. Take away the interaction and all you’ve got is people in funny costumes. Or in everyday clothes, in the case of modern larps.
Cosplay, by comparison, is something that would work really well in parades. Because it’s not about interaction, it’s about the costumes. It’s purely visual.
I think that efforts that display the interactivity, like the Robin Hood at the Joust idea or Grand Battle, will do much more to achieve public awareness and good will without requiring people to go too far out of their way to see it. With more marketing effort, something like that colonial NZ public larp I suggested a while back, or say a big public fairy carnival/faire larp for families for larp/interactive aspects, might work.
Leaving aside actually getting people to play in larp-like events, the other public relations effort that I think would work is getting continuing positive media coverage of larp events, especially events that have socially constructive content. Arty, educational, experimental and politically aware content. Stuff that doesn’t look geeky (like fantasy) or creepy (like vampire) with the negative stigma that accompany those genres. I’m not saying that there’s something wrong with those genres or that we shouldn’t play them (I like fantasy), but in the soundbite world of the media it pays to put your best foot forward. Pirates fits the bill. Nibelungen might. Can’t think of much else being run at the moment that does.