@Brian ******
i have travelled to Thailand to visit my girlfriend on many occasions over the last three years always on a 28 day visa (actually i think it's a 30 day visa) i have nev had any problems, although if we stay in a hotel anywhere then they do a TM30 when they take my passport, i know it's not what you are supposed to do but the general consensus is that if you don't need to go to immigration for anything then you should be ok, just be prepared to pay a fine if you get caught ( this could be in a police traffic stop or similar). I'm applying for my non immigrant OA visa in march next year and im visiting Thailand this October. Up to you really, yes you are supposed to do it, but for a 28 day visa you should be ok.