We are trying to rough-tune our December visit to the North of Thailand. I have a couple of question with regards to driving time.

Not counting sightseeing, can anyone provide the rough driving times between Sukothai, Chiang Mai and Mae Hong Son?

Thanks in advance!

Trip between Sukhothai and Chiang Mai takes about 4-5 hours, the roads are pretty big and in good condition. Chiang Mai - Mae Hong Son, I would allow a day. They say there are over 3000 bends in the road, but it seemed like a lot more to me and they are pretty steep to make it a bit more interesting. Expect lots of gear changing and getting stuck behind slow moving pick-ups.
On the Chiang Mai side the roads are in pretty good condition, but when you cross the border into Mae Hong Son, the holes in the road get much bigger.

Its a great drive though, definitelty recommended, Day 1 Sukhothai - Pai. Day 2 Pai - Mae Hong Son, worked out well for us.

Thanks for that. It confirms my thoughts that trying to get from Sukothai to MHS would be just too much for a day, especially when that is to be a sightseeing, stopping, and having fun, day.

We'll be running through Pai a few days later, as we go over to Chiang Rai, so maybe we will look more towards Mae Sariang. Still open....

We drove(actually a driver drove us)from Mae Hong Son to Chiang Mai via Pai in about 5 hours. That was with only 1 quick(10 min) stop.

From Sukothai to Mae Hong Son is definitely too much in one day. Just a warning however. The accomodations at Mae Sariang are not deluxe -- or at least they weren't a few years ago. Enroute you might want to see some of the Burmese refugee camps.