Yeh, side with yes man, but you can still kill benny in anyway you can. With yes man you rule the strip and even have your own army, and it's one of the better options for the good of the wasteland post playthrough.
oh i already killed "mr. i cant kill a guy with a head shot", i kept my convo with him very brief, just told him it was time to die and i ended up taking everyone in the casino down with him.....on a side note, spiked knuckles are fantastic, even with my character who has 11 under hiss unarmed skill. 2-3 hits and each chairman and body guard was down.
but now im excited to know that i can kill everyone and be rewarded for it. except brotherhood, and the boomers they ok in my book, heck maybe after everyones dead me the boomers and the BOS can take the boomers curiously put together airplane and see what the mexican wasteland is like.