Last few levels camera are everywhere so it's really easy to drag Big Daddies to them.
Typically I would hack them to be safe and then tag a Big Daddy with bullseye and watch the show.
2 tag = dead big daddy.
If the Big Daddy stops short of the area the camera watchs over you can actually either convince it to come a little closer by walking close to sister or just shoot the daddy and then retreat and as soon as he crosses the camera path bots will attack it ( but if you had to shoot him he will attack you in btw bots and focus on you once bots are dead).
I only actually fought straight on the second Big Daddy and the last 3 ( which I totally destroyed, 5 exploding arrows + half a tank of electric gel and the Big Daddy have no chance).
PS3-Xbox360 gap : 1.5 millions and going up in PS3 favor !
PS3-Wii gap : 20 millions and going down !