We have three across - although we do tend to make it two across and spread out into our individual sections at bed time! Did consider a bolster, but felt it would be maddening (and suspect he'd always pinch it).
We have two long ones. They cost a fortune and only the shop we bought them in have the same size pillow cases. Mind you our matress is 2 and a half foot deep (I'm only 5 foot 4 and have to climb up to bed) and the sheets for that are .. supplied only by the same shop ...
We must have had mug tattooed on our foreheads when we bought that bed.
John Lewis sell super kingsize pillows (not expensive). We have two which are a perfect fit widthways on our 6 ft bed, then we have two normal sized ones on top of those and finally two large square ones. Bed looks a bit like Mount Everest. DH only likes one pillow to sleep and tosses the others on the floor at night.