If they keep marriage, I'd like to be able to show my spouse some affection. I don't need sex or anything graphic, just the ability to kiss them (simple animation or cutscenes) or giving gifts like Quick-Thief said.
And please keep some of the spouse's original personality. None of this "I'm a tough warrior, but I'm married to the Dragonborn, so I have to be subservient" crap. I want my spouse to have sass, damnit. It makes the game more fun.