Thailand

Thailand is a new point on our travel map. We don't know anybody there, (other than a nice person I had a random Skype conversation with) and don't know much about it. So asking around I've gotten the following conflicting advice:

A kind lady who came to our yard sale said go to northern Thailand, not Bangkok. ChangRai is good place to fly to, much more rural. The other big city is ChangMy, also too big. Try the
ancient cities tour.
Tour companies:
General Tours
Asia tours.
Asia hotels books rooms in Thailand

On the other hand Jeff Martin (Universal Telecom, US pops) says the mountains up N are hot, and have the hazards of heroin traffic. Not a good place to go trekking. Also the beaches around Bangkok are notorious child prostitution areas. The beaches south, on the Bay of Thailand (?) were good family oriented slightly touristy.

So what to do? We have about a week there. Also hoping to get some dental work done there.