Can anyone advise the best route to Mae Sai from Chiang Mai, is it on the 118 to Chiang Rai or do I go the slightely longer route via Phayao?

Can anyone advise the best route to Mae Sai from Chiang Mai, is it on the 118 to Chiang Rai or do I go the slightely longer route via Phayao?

That all depends on whether you want to get there quickly or otherwise.

You could go via Mae Rim, Chiang Dao, Fang, Chiang Rai or via Mae Jo, Phrao and left via Chiang Dao or right via Wieng Papao to Chiang Rai. Or you could go via Lampang, Phayao etc.. The fastest route would be through Doi Saket, Mae Kachan, Chiang Rai then onto Mae Sai.