@Lo***
, the thing is you get no more time in country doing 30 day extensions on the 60 day stamps an METV gets you.
All you're doing is just burn downing the time the visa is valid for.
In Chiang Mai you can border-bounce to the Mae Sai - Tachiliek border, stamp out of thailand, stamp in&out of burma (for 500baht or $10USD) and stamp right back into thailand to get another 60 day stamp.
Most people on METV's who get here shortly after the visa is issued can wring almost 9 months of stay out of it by timing their border-bounces and extending the very last 60 day stamp by 30 days.