The one advantage of a monopoly is that the pricing is controlled and predictable, so a better room always costs more than a worse room ... and there is little gaming of the system. So you can rest easy that your more expensive hotel will be better than the less expensive option. Whether it is worth it depends upon your taste. Personally I think Sails in the Desert is worth it (but don't expect Southern Ocean Lodge quality of experience, even for the most expensive option).