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

Day 1: Arrival and Marina Bay Sands

• Arrive at Changi Airport and check into your hotel
• Head to Marina Bay Sands, one of the most iconic landmarks in Singapore
• Take a stroll along the waterfront promenade and enjoy the stunning views of the city skyline
• Visit the Gardens by the Bay, a beautiful nature park with futuristic Supertrees and indoor gardens
• End the day with a light show at the Marina Bay Sands Skypark Observation Deck

Day 2: Sentosa Island

• Start the day with a visit to Universal Studios Singapore, an exciting theme park with thrilling rides and attractions
• After lunch, head to Sentosa Island, a popular resort island with beaches, attractions, and entertainment options
• Visit the S.E.A. Aquarium, one of the largest aquariums in the world, and see over 100,000 marine animals
• End the day with a spectacular light and water show at the Wings of Time

Day 3: Chinatown and Little India

• Begin the day with a visit to Chinatown, a vibrant neighborhood with colorful shophouses, temples, and markets
• Explore the Buddha Tooth Relic Temple and Museum, a beautiful temple that houses a sacred relic of the Buddha
• Have lunch at a hawker center and try some local dishes like chicken rice or laksa
• In the afternoon, head to Little India, another colorful neighborhood with Indian shops, restaurants, and temples
• Visit the Sri Veeramakaliamman Temple, a stunning Hindu temple with intricate carvings and colorful statues

Day 4: Museums and Shopping

• Start the day with a visit to the National Museum of Singapore, which showcases the history and culture of Singapore
• Next, head to the ArtScience Museum, a unique museum that combines art, science, and technology
• Have lunch at a trendy cafe in the hip Tiong Bahru neighborhood
• In the afternoon, go shopping on Orchard Road, Singapore's premier shopping district with luxury boutiques and department stores
• End the day with a visit to Clarke Quay, a lively riverside area with restaurants, bars, and nightlife

Day 5: Nature and Food

• Start the day with a visit to the Singapore Botanic Gardens, a UNESCO World Heritage Site with beautiful gardens and tropical plants
• Have brunch at a local cafe and try some traditional Singaporean breakfast dishes like kaya toast and soft-boiled eggs
• In the afternoon, take a food tour of the city and sample some of Singapore's famous street food like satay, chili crab, and roti prata
• End the day with a relaxing river cruise along the Singapore River, where you can enjoy the city skyline and see some of the historic landmarks.