Yakuza games - bystanders reacting to revelations or side-missions, Haruka holding your hand when you explore the city with her, and adding those little details to make the city look to its real-life counterpart is pretty damn impressive.
Also the GTA series; it's the little things and jokes that make the series special.
MGS2 is one of my favorite games due to the little details and easter eggs. Snake/Raiden stepping on every step when going up or down the stairs, ice melting over time, leaving wet footprints, etc.









