Dope aloha shirt BTW.
Enjoy your time outside of Waikiki. I agree with Beau Vine -- you'll dig the rest of Oahu. Traffic will make you want to kill yourself, but you'll probably see a rainbow along the way so it's not all terrible. If you decide to cross over the pali (cliffs) on your travels, each highway is cool but the H3 is jaw-dropping and the Pali highway from Kailua has a decent lookout spot and a few spots to pull off and hike along the Nu'uanu valley streams and pools (just look for lots of cars parked). Don't leave anything valuable in your car if you park anywhere along the Pali Hwy though as it's known for smash and grabs.
Also forgot to mention Liliha Bakery for cream puffs and Leonard's for malasadas. Line for Leonard's is sometimes stupid though. If you're driving past the location on Kapahulu and the line doesn't go too far out the door it's worth stopping.
Diamond Head and Koko Head are both decent hikes but they are full sun and mostly straight up and down. From your base in Waikiki I'd either hit Manoa Falls (shaded, waterfall, get there before 9 for parking), Makapu'u lighthouse (full sun, not as steep, oceanside), or the Maunawili trail (very small pullout parking area on the Kaneohe-bound Likelike Highway, shaded, tropical, breezy, great views, don't leave anything in the car). Manoa and Maunawili offer your classic Hawaii jungle-esque experience. There's a cool spur trail off the Manoa Falls trail that takes you an hour up the pali but if it's been rainy at all it will get crazy muddy. Still the payoff is pretty great: