It used to be that arranging for seating in the kitchen simply meant leaving enough room for a small table and some chairs. But with the increased popularity of the "social" kitchen where the kitchen party truly never ends, we are facing the greater challenge of properly integrating seating into the actual kitchen cabinets. Whether it's a kitchen nook or a raised bar at a kitchen island, it is important the diners in the kitchen are comfortable where they're sitting, and that the kitchen will continue to function with seated diners in it.
We've already dealt with NKBA Kitchen Design Guideline #8 in a previous post, but the issue is important enough to bare repeating. At minimum we need to allow 32" between the counter space and any wall or obstruction behind the diner. This would simply allow the diner to be able to get in and out of the dining area and doesn't account for anyone wanting to get past this diner. To allow for movement behind the seated diner, 44" is required (the guidelines mention 36" if you want to "edge" past, but who wants to do that?). In terms of Universal Design standards allow for 60".
As for width, the Guideline asks for 24" per diner. More is better, but if you're trying to determine how many people can sit at the island 24" will give you a good approximation. Keep in mind that if you're seating area has a corner in it you cannot allow 2 diners to occupy the same corner.
