If you want to go somewhere off the regular route, find an empty Baht Bus and negotiate a fare with the driver before you get on. But don't put one foot inside the vehicle until you make sure the driver knows where he is going! Once and only once did I jump on a baht bus without first double checking.
After passing the same bank two times I began to feel suspicious and rang the bell many times before the driver actually halted the vehicle. When questioned about the route taken he replied "Too much traffic". He then admitted, with a grin, he didn't know where the place was.
You can hire a Baht bus to take you just about anywhere. Use them like you would an un metered taxi however if your travel time exceeds 35 minutes I'd advise you to hire a minibus or car with driver.
If you are traveling alone you could negotiate a deal for the Baht Bus front seat beside the driver if it is vacant. I did this once. When the driver realised I could speak Thai he didn't stop talking for the whole 40 minute journey. I sat back and enjoyed the air conditioning.
Sitting for long periods in the back of a Song Taow (some have low roofs which make you bend your neck or back) can make you tired or ache a little on reaching your destination. OK if you are rehearsing for the roll of Hunch Back of Notre Dam.
Two friends and I once used a Baht Bus to travel from Pattaya to Sriracha, a thirty five minute ride to have dinner at a restaurant. Something I didn't realise until we were well on our way at a very high speed was the leaking exhaust. Diesel fumes on an empty stomach for 35 minutes can make one feel rather nauseated.