What is the best place for a border run or visa extension from Chiang Mai?

@Cody ********

, your understanding is incorrect :/

There is no such thing as a 30 day tourist visa :O

IF you showed up here without having bought a visa from a thai consulate in your country before hand and were stamped in for FREE for 30 days you were stamped in on what's known as a 30 day visa exempt entry.

Be that as it may, you can go to the immigration office and get a 30 day extension for 1900baht at the immigration office.

After that you either go to a thai consulate in another country and BUY a single entry tourist visa OR you go to a border, stamp out of thailand, stamp in&out of another country and then back into thailand to get a new 30 day visa exempt entry stamp

Mae Sai is good for border run, but you can not apply for a new visa there as there is no thai Office on the burmese side of the border. But border run should be fine and will probably give you 30 more days (depending on your nationality). Going to immigration Office in Chiang Mai to get an extension is also a good option!

Just go to the immigration office and make a extension, so you get 30 days more without making a boarder run and it cost 1900 baht

I am not clear what you are asking. Most from Chiang Mai do a border run to Mai Sai.