Just the the two of us in a booth, or at a small table - across
Just the two of us at a standard table - usually on adjacent sides
When out with others - it varies:
If it’s a booth with one other couple, next to each other.
It it’s booth with DS, he usually sits with me and DH with the coats.
If it’s a large table with lots of people, usually either next to or across, depending on what everyone else does, but sometimes not either one.