Pai is several hours from Chaing Mai (about 4 hours or more by van). It is well worth the trip. I spent about 10 days there and enjoyed it, it can be quite trendy in the core of that small town,but there are many layers to the experience. So many inexpensive guest houses just out of town. Some travelers stay for weeks or months there. Note: The road winds through the mountains and makes most a bit nausious. I went farther east & flew back to Chaing Mai, as the trip was rather inexpensive, took 40 minutes & didn't give me motion sickness.
I hope that helps...R about 5 years ago