Here are some random ones that I can immediately remember:
Some of the furniture, for example the heavy chairs they bring out when there's a line at the front desk. They're similar to the furniture in the bar.
The off-center entrances to some of the restaurants and function rooms.
General built-in furniture and lighting fixtures on the walls.
Floor to ceiling windows, for example on the left side as you enter the main building (IIRC looking out onto a small rock garden). Once there was a history of the Imperial Hotel display here (inside).