Hello, great choice for your travel destinations! The natural beauty of Chiang Mai, Pai, and Mae Hong Son is absolutely breathtaking. Here are some travel tips for you to consider:

Best Time to Visit:
The best time to visit these places is during the 'cool season' from November to February, when temperatures are more moderate. This period also features lantern festivals of Yi Peng and Loy Krathong which are an amazing experience in Chiang Mai.

Route and Accessibility:
You can fly into Chiang Mai directly via its International Airport, from which you can rent a car, take a bus or hire a taxi to get around. Pai and Mae Hong Son, are accessible from Chiang Mai via highway 1095, though be warned - it has over 700 twists and turns!

Accommodation and Booking:
There's a variety of accommodations available from luxury hotels, guest houses to cozy homestays. It's recommended to book your stay in advance especially during the peak season. Airbnb and Booking.com are good websites to check out listings.

Clothing and Essentials:
As these places are often cooler than the rest of Thailand, it's advisable to pack a mix of light clothing with a couple of warm layers. Don't forget your swimwear for hot springs in Pai and essentials like sunscreen, bug repellent, and a sturdy, comfortable pair of shoes for trekking.

Health and Safety:
Basic healthcare facilities are available in these cities. However, for more serious issues, hospitals in larger cities like Chiang Mai are recommended. Also, avoid tap water and be cautious of street food hygiene, especially in more rural areas.

Local Etiquette and Respect:
Thai people are generally polite and hospitable. Wai, a slightly bow with palms pressed together, is a common form of greeting. When visiting temples, make sure to dress modestly and take your shoes off before entering.