I'm a family of 5 and routinely book two rooms.
Only a few domestic locations but from experience,

Rooms have always been adjacent or interconnecting.
-Always upgraded but definitely "1" category only as it was a preferred view at best.
-4pm checkout always offered for both rooms.
-$20 food/bev credit was only 1 room except for NYC gave me $40.

SF(both), LA, Monterey, San Diego, Boston, NYC(Time Square), DC.