This is how we explored Thailand. It may help you to make your itinerary. Day 1: Arrived in Bangkok, immediately took a bus to Pattaya. Day 2: Full day exploring Pattaya: local attractions, beaches, and nightlife. Day 3: Travelled back to Bangkok to catch a flight onward. Day 4–5: Spent two nights in Phuket, enjoying beaches, island tours, and local cuisine. Day 6: Flew from Phuket to Bangkok. Day 7: Full day exploring Bangkok: temples, markets, and shopping. Day 8: Took a bus to Chiang Mai, stayed for two nights. Day 9: Continued enjoying Chiang Mai, then travelled by bus to Kanchanaburi and stayed overnight. Day 10: Took a train back to Bangkok, explored the city's nightlife. Day 11: Day trip to Ayutthaya by train, returned to Bangkok in the evening. Day 12: Departed from Bangkok to Delhi.