I have been to Thailand 10 times.
If you want the real lady´s, you will have to go clubbing in Bangkok, go to the more expensive clubs and you will find them. They are starting to like the more muscular shredded guys, so go for it. They don´t like the chubby/fat ones.
The problem about going to tourist areas and pick up lady´s are many are for sale there, of course you can find normal lady´s too, but´s really difficult. That´s why bangkok are the best place to meet them, check out siam2night.com and you will see what I´m talking about, the pictures from the clubs there should give you at hint where to go to, also Bangkok have clubs for all kind of music taste.
Getting aids from a Thai prostitute is not something you should worry about, I never got a STD or aids from any of them and I have fucked many without condom or broken many.
I can also recommend thailovelinks.com if you want to set up a date before, I have done it the last 2 times I have been there and meet some really nice lady´s. My X GF was from that site and smoking hot!!