This is a big one. If one half is a light sleeper and the other a heavy sleeper, then you might be surprised to find that the type of mattress can make all the difference. The heavy sleeper might be restless, rolling and tossing and turning all night, thus keeping their light sleeper partner awake.
A firm mattress absorbs the energy of motion, preventing motion transfer better than a softer mattress. Memory foam beds do this as well.
This way, if you have to get up for a Jimmy Riddle in the night, you’ll create less of a jiggling disturbance. A disturbance that could waken your peacefully sleeping partner, both in the exit and the return.