Begin your trip by visiting Chinatown, Bangkok which is known for its food and shopping. After that, explore the Golden Buddha Temple and Wat Pho, where you can see the largest collection of Buddha images. In the afternoon, head to Sea Life Bangkok Ocean World for an underwater adventure.
Visit the ancient capital city of Ayutthaya and explore the Bang Pa-In Royal Palace, Ayutthaya Historical Park, and Wat Yai Chai Mongkhon. Don't forget to try the delicious street food at Ayutthaya Night Market before heading back to Bangkok.
In Chiang Mai, explore the Doi Suthep-Pui National Park, visit the Chiang Mai Zoo for some up-close encounters with wildlife, and experience the Flight of the Gibbon for a thrilling zipline experience through the jungle.
Take a tour of Phuket, explore the Old Phuket Town with its Chinese temples and architecture. Then visit the Phuket Aquarium to see a variety of marine life. Take a dip in the sea at Patong Beach and end your day watching Simon Cabaret Show.
Visit Koh Samui and relax on the beautiful Chaweng Beach, try snorkeling at Ang Thong National Marine Park, and explore Wat Plai Laem, which has a massive statue of Guanyin. End your day at Big Buddha Temple for a stunning sunset view.
If you have additional time, consider visiting other family-friendly attractions such as Safari World Bangkok, Khao Yai National Park, and Phang Nga Bay. If you have less time, consider removing a few destinations and spending more time at the remaining ones.