A collared shirt and khakis are fine if you are not participating in the Formal Night in the main dining rooms. Khaki pants do not, by no stretch of the imagination, fall in any category of formal attire. I know there are some who wear khakis and a collared polo shirt to the dining room on formal night, and pride themselves on "getting away with it." But now and then then will be a stricter maitre'd or head waiter who turns them away because their attire does not fit the guidelines.

In my experience, dress on formal nights on Med cruises tends to be more formal. Perhaps that's because there are generally some European cruisers onboard, and they seem more apt to comply with Princess recommendations regarding formal night attire. Some passengers, whether American or European, go all out, with lovely evening gowns and tuxedos. Seeing people all dressed up changes the atmosphere of the ship into something more gala. The phone in the room can be used for an automated wake up call. It has to be programmed though. Instructions are by the phone.