Start your day at Chatuchak Weekend Market, a great place to shop for Thai souvenirs and try local street food. Here you can find everything from antiques, clothes, and jewelry to exotic pets and furniture. Later, make your way to Wat Phra Kaew, a must-visit temple, which houses the iconic Emerald Buddha.
Visit Ayutthaya Historical Park, a UNESCO World Heritage site, and explore the ancient ruins of the former capital of Siam. In the evening, head towards the bustling backpacker hub Khao San Road. Experiencing the vibrant street life of Bangkok, which is peppered with street vendors, food stalls, bars, and live music.
Visit Wat Arun, also known as the "Temple of Dawn". This iconic temple is decorated with colorful ceramic tiles that sparkle in the sun and provide a beautiful photo opportunity. Later, spend your evening roaming around Chinatown. Here you can find a variety of Chinese food and markets selling gold, herbs, and Chinese Traditional medicines.
Visit the Erawan Waterfall, one of the most beautiful waterfalls in Thailand, located within the Erawan National Park. Enjoy swimming in the crystal clear pools surrounded by lush vegetation and scenic landscape. Later, Visit Kanchanaburi and take a boat ride on the River Kwai, a place steeped in history during WWII.
Head over to the beautiful beach of Koh Samet. Soak up the sun, swim in the turquoise waters, and indulge in delicious seafood. In the evening, make your way to Pattaya, a popular beach destination, and enjoy the lively nightlife scene full of bars, clubs, and activities.
If you have more than 5 days, consider visiting Chiang Mai, the cultural hub of Thailand, or the islands of Phuket, Koh Phi Phi, or Koh Samui. For those with less time, you can always shorten your trip or skip places/ activities and adjust accordingly. Additionally, try to take public transportation wherever possible to save money, or consider renting a scooter for a more adventurous option.