Assuming it is very late in the game:
With the tying run at the plate, unless there is ABSOLUTELY NO chance that batter is going to get a hit then they HAVE to swing away to get on base. The fielders can ignore the runners for the most part as they mean little really.
Early in the game - it may depend on whether I feel we are going to develop more chances to score against the opponent or not. If I feel bunting over the runners to give a better hitter a chance to drive them in I may think about it if I feel we are going to get multiple opportunities to score during the game.