We were fortunate to do this in late Nov./early Dec 2011 and we had Jermsak as our driver/guide for 7 days. He was THE BEST!
I'm sure others will tell you how they did it by public transportation.
Remember this: The road to Pai from Chiang Mai has many curves!!!!!!
I drove this myself but the weather was pretty bad and the windscreen wipers on my rental car were in very poor condition,so it added a bit of time to my trip. I also travelled at night and even though I used to drive long distance at night professionally,I found that the concentration required wore me out & I stopped for a break overnight in Chiang Mai. It's a very pretty drive so worth doing during the day,especially along Highway 1095. There is certainly public transport available from CEI to CNX though Ive never used it.Once you get to Chiang Mai I would suggest taking a public bus to Pai from the Arcade Bus Station.They cost about THB160 per person each way & I feel much safer than being in one of the silver private minivans who often drive like crazy. The bus drops you off basically in the centre of Pai town.
Can't help you with the public transportation from Chiang Mai to Pai, but Chiang Rai to Chiang Mai is about 3 hours by bus, maybe slightly longer. Many travelers on this forum use the Green VIP bus as it is a bit quicker and a bit more comfortable, but there is also a "regular" bus.
I can concur with Morewierd that Jermsak is a safe and reliable driver/guide, but a driver/guide will be more expensive than public transportation.
I am planning a trip in that direction. My route, once I get to Chiang Rai, will be to travel to Mae Salong and stay overnight there, then on to Doi Tung and then to Mae Sai, overnight there and then drive to Pai the next day. Having not made the trip before, I don't know how curvy the road is, but it can't be as windy as the route from Chiang Mai to Pai.
As another poster has said, it's much better to travel in daylight so you can see the beautiful scenery. I will be hiring a guide/driver for 7 days to do a trip starting in Chiang Mai, then up to Chiang Rai where I will spend at least 1 or 2 days, as there is much to see in the area. If hiring a driver/guide is of interest, check the FAQ section top right for reviews and recommendations of guides. Joy and Jermsak are very good. I have heard that the buses are not too regular from Chiang Rai to Mae Salong - I don't know about Chiang Rai to Pai... but it is a different and interesting route than from Chiang Mai to Pai.
AYA have a direct service from CR to Pai, it leaves mid afternoon arriving at 8 pm, would advise you get the VIP bus from CR into the arcade bus station, the the Pai bus leaves from the same. I will enquire tomorrow to see if you can pre book the last leg at CR.
A private mini bus will set you back 6,000 baht, a guide will be much more.
Thank you everyone for your advice. What is at Mae Hong Son and should we be going there?
Not familiar with these areas so trying to research as much as possible. We are keen to visit areas other than Chiang Mai as we've been there a number of times. Any advice would be welcomed.
Thanks in advance MCG
Also,Pai is fairly quiet in the off season... Best time to go seems to be December,otherwise a lot of places are shut and the charming night market is only on about half steam!
Pai (IMO) is a tourist trap. Mae Hong Son is another 3 hours beyond Pai through the mountains and is a unique small town. Being unique, its nothing like anywhere else in Thailand, and has some beautiful wooden buildings and temples in a style heavily influenced by Burmese styles. Its a wonderful small mountain town with a picturesque lake, narrow streets, shops, cafes etc, and is virtually unspoiled despite getting a good number of tourists.
I didn't realise that Mae Hong Son was so nice. We might give that a try instead. What do you suggest is the best way to get there. We are flying into Bangkok and then flying north from there. Do we fly into Chiang Mai or can we fly into Chiang Rai? Haven't been to Chiang Rai so keen to have a look and then move onto Mae Hong Son from there. Is that a doable thing?
Sorry about all the questions, but keen for advice from those who know. Thanks again