Splitting hotel nights on Oahu between Waikiki and somewhere else could work well for some visitors. It's less expensive and much less of a hassle than flying to another island for part of the vacation, but provides many of the same advantages.
Of course, if using points, five nights is the sweet spot because the fifth night is free. In that case, it's still possible to stay one place for 5 nights and several nights at another place -- with one of those places being Waikiki, and the other one not.