General rule : The platform size should be 2-3 times the wavelength in the area of operation or it will track the waves what makes live aboard VERY unpleasent.
I was thinking about the same but decided that best rule is to take in account the biggest wave. not close to the shore waves (cos they can be even 85 meters – 279 ft in height) but in the middle of the ocean.
I tend to think about the need to choose the larget dimensions of the platform to avoid the need to run away from storms and waves. especially if ones intend to create more than one platform. But the city