Mae Sot can be a fun place. It's certainly changed a great deal over the last twenty years. It used to be totally lawless town, anything went. It's better controlled now and the dodgy stuff isn't as flamboyantly run as it used to be.
There's even a Tesco/Lotus there now, nice set up too.
Plenty of decent accommodation in and just out of town, I have some photographs I'll put up asap, nice bungalows for about Bt500 per night.
There's a decent {very decent }hotel just a couple of miles outside of town, everything going beautiful place, swimming pool all the lot, prices were very fair if I remember correctly, Central Hillside Hotel from memory (and that's fading). Good food, all the trimmings!
In Myawaddi, there are some good bargains, especially on old British antiques if you feel that way inclined. The gems are cheap too, but I suppose you need to know what you are buying. I don't really understand the values, so I'm a bit hesitant in laying out for what could be a piece of flash glass?