Sometimes I will pan them dead center, sometimes I will leave them stereo, sometimes I will pan them hard left or hard right. It all depends on the record.
I do find often that records I mix have stereo pads that simply aren't wide enough and I have to widen them. Often I will just do a mid-side adjustment, or I'll do a hass delay. Whichever works better. I have other tricks for making a pad wider and get it out of the center, but those are the two most common. I think a lot of "beatmakers" really don't understand how to make sounds so that they work with vocals because pads with stuff piled up in the center is a common problem I run into while mixing.