I currently live in Kuala Lumper, Malaysia and have visited Bangkok Twice. Once in the late spring and once in late summer. The temperature was about the same. The first visit, I took 9 students for the World Scholar's Cup around the end of June. We stayed at the 93 hotel in the Pratunam area. Every day we walk to Center World, many times the rounds did not get over untell well after 10 PM. We encountered absolutely no problems with the locals or with prostitutes. On our day off, we walked all over the garment district and again no problems.
My second trip was in the middle of August, my daughter and I stayed at the Amaze Hotel in Sukhumvit area. We traveled all over central Bangkok and again the Pratunam area. No Problem with the locals or with Prostitutes. No one was handing out pamphlets. I enjoyed Bangkok, the people are warm and friendly and most of the time willing to help. I have seriously looked at teaching in Thailand. While there, I did not experience any pollution, unlike KL. The rivers were clean and free of debris, unlike KL, the streets were clean and free from rubbish, unlike KL. Not many Thia's speak English so if you choose to teach there you will need to learn some language. KL is easier in this respect. Try to look up expat blogs about an area, they will tell you like it is. Thailand is cheap to live in. Bangkok is a central location for making short trips to other Asian countries. Make sure you are making more than the 30,000Baht so often offered. 60,000 and above is a good salary.
Good Luck with your choice.