Is a 60 day tourist visa the longest visa a tourist can get?

Yes, 60 days is the longest. You can extend your stay with additional 30 days at your local immigration office for 1,900 Baht. Total 90 days.

You could also apply for a double entry tourist visa, in case you woulkd need a border run after 90 days to get another 60+30 days. Total stay 180 days.

The Tourist visa can also be issued as triple entry.

George, I'm a little confused about the double, triple entry visa could you please explain how that works? I understand the 60 plus 30 day extension.

After the 60 days plus 30 extension, you cross a border, come back into Thailand, and start the next 60 plus 30 days.