The only reason I’d imagine visitors wanting to stay on the west side of Oahu would be to get away from the city. It’s more than 45 miles from Waikiki (about an hour of driving one-way), so it’s likely you’ll want to do things on that side of the island.
Makaha is probably the farthest and most secluded you’ll get from the city life. There’s a resort in the back of the valley and vacation condos on the beach. We stayed at the Makaha Beach Cabanas once as kids and loved how it was literally just steps from the ocean. Every night, we’d fall asleep to the soothing sounds of the water outside.
I remember seeing humpback whales one morning from the lanai and turtles swimming near the rocky cove below. There’s a long stretch of white sandy beach that never really got crowded either, except for a few families having a beach day. You can walk to the point for the best view of daredevil surfers. I’m pretty sure in the summer months, or on calm days, it’d be a great place for snorkeling.
Keep in mind, you’re in an isolated part of the island, so the area beyond the beachfront property isn’t the most tourist-friendly. As in, there are not many places to eat or shop. It’s pretty much just a few corner markets, some fast foods and drug stores; nothing like what you would find in Honolulu.
Best bet would be to buy groceries and cook your own meals if you have a kitchen in the condo or eat out in Kapolei or Ewa. Both towns are about a 25-minute drive from Makaha and have multiple shopping centers. In fact, Kapolei has been called the “second city” of the island, with new chain stores being added every other year. Olive Garden will be the next addition to eateries.
You may choose to split your vacation time in half; the first half staying in Waikiki doing city stuff and the second winding down on the west side. Whatever you decide on, it will no doubt be a memorable trip.