I am from US. I am planning on staying 4 months. I can come on retirement visa, however is there any other options. What is the longest you can stay with a touist visa?

Thanks

Each entry is for 60 days, and can be extended for 30 days for 1900 Baht. You could apply for a double entry before your trip, with a border run that would allow a stay of 6 months.

Are you planning more than one trip within the year? If just one the above 2 entry tourist visa seems to be the best option. Retirement is expensive (with medical/police reports and cost of visa and would only save a quick border run).

I think double entry tourist visa will be the best option for you or single entry for 60 days + 30 days extension in immigration office.