Most hotel rates in the US are based on double occupancy. If you look at the fine print when booking, you can be subject to extra fees for more guests. Most hotels are very lenient about them, some are sticklers. I can see Cabana Bay and Sapphire Falls being lenient because Express Passes aren't available at those hotels, but I wouldn't be surprised if you see the fees at the other three hotels.
Essentially, YMMV.