What officer rank do you call a room to attention in the air force?

When any Warrant or Commissioned officer enters a room, unless there is another officer of the same of higher grade already present. Please note that in certain rooms, such as a dining area or bathroom, rather than "Attention" the proper command would be "At ease".

Generally, you call the room to attention only if a officer entering the room is of a higher rank than the people already in the room.

For example, if the room is only filled with enlisted people, you would call the room to attention if an officer of any rank entered the room. Even a 2nd Lieutenant.
If, say, a Lt. Colonel is already in the room, and a Major enters, you would NOT call the room to attention. However, if a full bird Colonel enters, you WOULD call the room to attention.

It is common for officers to excuse a room from calling to attention if they plan to enter and leave a lot. Rooms with a lot of activity, usually have an unwritten rule that the room is only called to attention for officer who part of the staff or regular visitors. In the Command Post, for example, pilots of all ranks are common visitors. The room would usually only be called to attention for O-6 and higher. Otherwise, nothing would get done.