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

Day 1: Arrival and Exploration

• Arrive at Suvarnabhumi Airport and check into your hotel.
• Take a stroll around the city to get a feel of the place. You can visit the famous Wat Arun temple, which is located on the west bank of the Chao Phraya River.
• In the evening, head to Khao San Road, a popular backpacker hub, for some street food and drinks.

Day 2: Cultural Tour

• Start your day with a visit to the Grand Palace, which is home to the famous Emerald Buddha.
• Next, head to Wat Pho, which is known for its giant reclining Buddha statue.
• In the afternoon, take a long-tail boat ride along the Chao Phraya River to explore the city from a different perspective.

Day 3: Shopping and Food Tour

• Visit Chatuchak Weekend Market, one of the largest markets in the world, to shop for souvenirs, clothes, and accessories.
• In the evening, head to Chinatown for some delicious street food. Try the famous Pad Thai or Tom Yum soup.

Day 4: Day Trip to Ayutthaya

• Take a day trip to Ayutthaya, the ancient capital of Thailand, which is located about 80 km north of Bangkok.
• Explore the ruins of the old city, including the famous Wat Mahathat temple, which has a Buddha head entwined in tree roots.
• Return to Bangkok in the evening.

Day 5: Relaxation and Nightlife

• Spend the morning relaxing at Lumpini Park, which is a beautiful green space in the heart of the city.
• In the evening, head to one of the rooftop bars in the city, such as Sky Bar or Vertigo, for some drinks and stunning views of the city skyline.

I hope this itinerary helps you plan your trip to Bangkok!