Hi mate, welcome to bkk. see this and your other posting.
There used to be more bj bars but covid made most of them closed down...
7-heaven is relatively new, and this place has been there for a while (used to be different name tho)
https://woodbarbangkok.com/index.html
I personally never tried those bj bars but i can imagine how its like.
7-heaven: seemingly offering younger, attractive girls who dont want to provide punting but bj to make ends meet
Wood bar: more matured ladies with amazing skills (according to my fellow japaneses... mid 50s or so). They are more relaxed, skilled.
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Except 7-heaven or Wood bar, i dont think there are much of places they say they offer that service (as long as i know, at least online)
But i can see there are plenty of places providing bj.
At some bars around Nana in soi 7/1, they just seem like an operating bar from the middle of the day, and ladies are saying they can give you massage, bj, sex, etc. they seem to have some rooms or area you can go in and enjoy.
(I used to tailor suits around there and had to pass through the bar areas thats why i know lol)
another option is just try the massage places and negotiate.
yet like other guys saying, they might not like to give 40 mins hj bj - as punting is much "easier" for them to make money.