We have been to Nachi twice and did Nachi and Royal Palm on our cruise this past spring break. We are beach people, btw.
We chose Nachi because of the limited number of guests, and the price seemed reasonable to us (especially with included food and unlimited drink).
We've vacationed at GC before, so we were familiar with area and 7 mile beach. We were iffy on whether we really needed a cabana, but after having one we were glad we had one. It was surprising how less crowded it felt just a few feet back with some privacy. And though not included, our food was delicious.