Hello! It's great to hear you're planning a trip to Chiang Mai, Chiang Rai, and Phetchabun. Here are some tips to help you with your trip.

Best Time to Visit:
The best time to visit these cities in Thailand is from November to February during the cool dry season. However, if you wish to witness the famous Yi Peng Lantern Festival in Chiang Mai, plan your trip in November.

Route and Accessibility:
To reach Chiang Mai, the most convenient way is to fly directly from major international airports. From Chiang Mai, you can take a bus or drive to Chiang Rai which is about 3-4 hours away. For reaching Phetchabun, you can either fly to Phitsanulok and take a taxi or bus, or take a direct bus from Bangkok.

Accommodation and Booking:
There's a wide range of accommodations available in these cities from boutique hotels to budget guesthouses. Use trusted online platforms like Booking.com or Airbnb to book in advance, especially if you're travelling during the peak season.

Clothing and Essentials:
Pack lightweight, breathable clothing for the tropical weather. However, if you're visiting between November to February, carry a jacket for cooler evenings. Essentials include mosquito repellent, sunscreen, a hat to protect against the sun, and comfortable walking shoes.

Health and Safety:
Ensure you're up-to-date on routine vaccines before your trip. Care should be taken with street food, drink bottled water only, and avoid mosquito bites to prevent diseases like dengue. Consult your healthcare professional about anti-malaria medication.

Local Etiquette and Respect:
Thailand is a Buddhist country and you should dress respectfully, especially when visiting temples. Always remove your shoes before entering someone's home or a temple. Avoid touching or passing things over someone's head as it's considered disrespectful.