If you think about sitting, it seems fair to say that where you're sitting is more important than that you're sitting. Sitting in a movie theater, sitting in a classroom, sitting in the driver's seat of a car, sitting in the defendant's seat at a trial, sitting at the family dinner table – those are very, very different things.
But even so, the fact that you're sitting in those places is important – it means you are part of what's going on, you're staying in place.
It is much the same with "sitting" in the Bible. Sitting on a throne indicates judgment; sitting in a tent door indicates holiness. The context is crucial. But in all cases "sitting" indicates a sense of permanence, belonging, and full participation in the spiritual state illustrated through the context.
(References: Arcana Coelestia 6423[1-2]; Arcana Coelestia 9422[1-3]; Apocalypse Explained 687[1-17]; Apocalypse Explained 687 )