Batman first. He uses the paperclip only to open the lock and sneak out.
MacGyver makes a small bow with the paperclip layed out as an arrow. He calls the guard over and shoots him in the eye in such a way that the guard will fall down with the keys next to the bars to the cell. He gets the keys and walks out.
Stark stares at the walls. He is executed.
~wickerman~
I think MacGyver would use the the paperclip to secure the straw to the rubberband that will hang in the window. The air currents will make the strat vibrate in such a way that it sends an SOS to nearby allied forces base.
Then he rigs the same rubberband, paperclip, and straw to blow the doors off his cell while the his allies attack the base to make his escape.