Special Requests are forwarded to the hotel when requested. Remember that these cannot be reserved ahead of time, they are provided to the hotel so that the Front Desk can do all possible to accommodate you but are subject to availability on your day of arrival.
Rooms with individual entrance doors from the outside and a connecting door between. Guests can move between rooms without going through the hallway.
Rooms with a common wall but no connecting door.
Rooms close to each other, perhaps across the hall.
Request a room on a higher or lower floor, close or far from elevator, etc.
Request a quiet room, or a non-smoking room (the vast majority of hotels today are non-smoking)