I would buy a big cardboard, cut a small hole in the middle, about 20" diameter and put it where you sit normally. Whoever's head and however many can fit in the hole will be in the sweetspot.
Speaker set up for more than 1 person
I have my system set up perfectly for a single person sweet spot. Near field about 9 feet from my speakers. But if I move even slightly off center the soundstage moves and one of the speakers dominates. If I have a couple friends over how can I arrange my speakers so we can all get a good soundstage with centered imaging? Move my speakers closer together?