Here's an ideal itinerary for 5 days in Oahu:

Day 1: Arrival and Beach Day

• Arrive in Oahu and check into your hotel
• Head to Waikiki Beach for a day of sun, sand, and surf
• Take a stroll down Kalakaua Avenue and check out the shops and restaurants
• In the evening, catch a sunset at Diamond Head Lookout

Day 2: North Shore Adventure

• Drive up to the North Shore and stop at the Dole Plantation for some pineapple treats
• Visit the Polynesian Cultural Center to learn about the history and culture of the Pacific Islands
• Stop at the famous shrimp trucks for lunch
• Spend the afternoon at one of the North Shore's beautiful beaches, such as Sunset Beach or Waimea Bay
• In the evening, head back to Waikiki and enjoy a dinner at one of the many restaurants in the area

Day 3: Pearl Harbor and City Tour

• Start the day with a visit to Pearl Harbor and the USS Arizona Memorial
• Take a city tour of Honolulu and see landmarks such as Iolani Palace, the State Capitol, and the King Kamehameha Statue
• Stop for lunch at one of the local food trucks or cafes
• Spend the afternoon at Ala Moana Beach Park or Magic Island
• In the evening, catch a show at the Hawaii Theatre or the Neal S. Blaisdell Center

Day 4: Hiking and Waterfalls

• Start the day with a hike to the top of Diamond Head for stunning views of the island
• Drive to the east side of the island and hike to the Manoa Falls
• Stop for lunch at one of the local cafes or food trucks
• Spend the afternoon at Lanikai Beach or Kailua Beach
• In the evening, head back to Waikiki and enjoy a dinner at one of the many restaurants in the area

Day 5: Relaxation and Farewell

• Spend the day relaxing at your hotel's pool or spa
• Take a walk through the Honolulu Zoo or the Waikiki Aquarium
• Enjoy a farewell dinner at one of the island's top restaurants, such as Roy's or Alan Wong's
• Depart Oahu with memories to last a lifetime!