Chiang Rai To Mae Sai
This is a popular "visa run" route, where you can cross the border at Mae Sai to Myanmar and reenter Thailand for another 30 days (as long as you have not been in Thailand for 60 consecutive days previously; you'll have to pay 500B). Most visitors coming from Chiang Rai zip through the little border town of Mae Sai on their way to the Golden Triangle and Chiang Saen, but the town is worth a stop. It is the northernmost point in Thailand.
Just to the right of the border gate to Myanmar (the end of the highway), you'll find a busy market area with rows of tacky souvenirs -- and silver jewelry brought from Myanmar. There is also a busy hotel used mostly by Thai tourists and gem traders, the Wang Thong Hotel (299 Phaholyothin Rd.; tel. 05373-3388; from 1,000B double). It has spacious rooms, a pool, a pub, and a dance club, and is almost hidden behind lanes of souvenir stalls. Warning: Don't be tempted by the offer of cheap rubies or sapphires, as such offers are almost certainly a scam.