This is the "local" side of the Oahu where haoles (folks of European descent) and good restaurants are hard to find.
You can find decent condo rentals on Makaha Beach for well under U$100/night, less expensive quarters up in the valley, condo rentals on Pokai Beach in downtown Waianae, condo rentals in Maili, and a handful of house rentals in Nanakuli. If you're willing to pay U$400/night, you can stay at Koolina but it's a bit too far from Makaha Beach or anything else on Oahu for that matter.
It's dry on the leeward coast, hotter than other parts of the island, but the hiking is great and Makaha Beach is one of the best all-around beaches in the world, if you're looking for active recreation. The mountains above Waianae and Makaha Valley offer some of the best hiking anywhere in the islands and the walk to Kaena Point is well worth the effort.
Wherever you go, take plenty of water with you, lock your car if you take one, and leave no valuables behind.