Until these designs include a moderate amount of self-sufficiency, they're not going to be cost-effective enough to get regular people living on them. This means you either have to aim for tourists or provide a paparazzi-free haven to celebrities.<p>Fishing would be mandatory for food and greenhouses would certainly be required, and preferably a well implemented vertical farming operation could do wonders. However, unless the scale is huge it would be difficult to become self-sufficient, especially if providing meat via cattle/pigs. Chickens are relatively easy to keep in higher densities and would likely provide a good supply of protein, providing you have the room to have the graze; incidentally, chickens are only generally destructive of grasses around their nest-site (where the chicken coop is) and are excellent pest controls. Without natural predators and with clipped wings, chickens could be allowed to forage in any open gardens. You'd be required to introduce worms, certain bugs and beetles, and bees anyway, so they'd provide supplementary nutrition to your chickens (free of cost and the chickens are a form of organic pesticide).<p>The economy would likely have to have a vertically integrated economy. Basically, you either need to seduce a whale (rich person/celebrity/etc) who'll spend money on services you're providing for a few benefits (major privacy), or you'll have to net tourists and take their money, or you'll have to have a huge export industry, likely through fishing. If you're choosing the latter, you might as well buy out or establish a fishing platform and work from there. It's been well established that oceanic platforms can act as their own man-made reef, encouraging fish growth in their area. Essentially, a well designed platform could be a self-fulfilling prophecy.