I've been living in On Nut area about 6 months.
Another poster mentioned massage places in this area with "extra" services, but I'm not aware of any.
As the previous BM noted, near BTS On Nut is soi 79, which is a small alley crammed with shops, vendors and massage places.
(from the BTS On Nut, walk about 500 meters back toward Asok direction to reach soi 79.)
There are maybe a dozen massage places in that alley.
These places tend to be busy at night, from maybe after 6 or 7 pm., when working Thais seem to patronize them after work.
Most parlors charge 150 baht for a one-hour, foot or thai massages, and 300 baht for oil massages.
They usually ask upfront if you want a two-hour massage.
These are straight massage places, with both male Thai and female masseuses.
Take care to specifically point to a female masseuse that you want the massage from, if you are choosy.
Otherwise you will get whoever is next in the rotation.
That's how I once ended up getting massaged by an older, small and muscular Thai guy.
Despite my homophobic misgivings, the guy actually gave me a good foot massage (and didn't go too far up my thighs with his oily fingers.)
He really used his muscle to break the knotted muscle tissue on my back, so that part was good.
In my experience, these are all straight massages, no hanky-panky extra service.
Generally, 50 baht is an OK tip, and 100 baht is very good tip.
The happy masseuse will probably urge, "You come tomorrow, nah?"
My personal recommendations:
As you walk up soi 79, about midway, to your left, is "Ban Lanna Massage"
A striking big and attractive country girl, "Tokyu" gives nice therapeutic oil massage.
A tallish and pale co-worker, "Nee" from Myanmar, has very soft hands and soothing touch.
Because there's so many parlors and masseuses, Tokyuu said she only averages 1-2 customers a day.
She is single, and lives at the massage parlor.
She seems content with her simple, narrow life.
The other place I want to mention is the last massage parlor at the end of soi 79, just before it ends at the Big C parking lot.
There are two big rawboned and cute twin sisters, "Ui" and "Aw."
"Aw" gives a powerful, back-kneading oil massage that really busts up the knots in your back.
"Ui" gives a strong "oil" massage too, but not as powerful as "Aw."
But by far, the best oil masseuse I've had in Thailand is "Nam."
She works at a massage parlor about a mile further up On Nut, close to soi 10, where I live.
"Nam" is a big pale, odd-looking sexy innocent cutie.
She is 28, not slim, somewhat athletic build but curvy.
Something about her pale muscular arms and playful girlish giggle turns me on, as I watch her working on my body.
Sadly, she has a boyfriend. Also, no hanky panky during massage.
Nam has marvelous strong hands, sensual and therapeutic, with very skilled and professional technique.
What separates Nam from the usual oil masseuse is that she uses her elbows to break all the hard knots in my back, mashing them into softness.
At times, I have to steel myself against involuntary wincing from the pain. Hurts so good!
Cost for oil massage: 350 baht, for one hour. Usually I give 100 baht tip.
Maybe someday I'll treat myself to a two-hour blissful oil session with Nam.
Yet, the 700 baht cost (plus 200 tip) would equal a BJ from Kasalong or Lolita's.
Ah the tradeoffs: a 15-minute penile tongue massage vs a 2-hour full body sensual massage from Nam.
The directions are a bit complicated, if you care to seek Nam out.
The massage parlor is called, "One Fine Day,"
It's located on On Nut road, just before soi 10, where I live.
You could take a songthaew going up On Nut road that passes by the parlor, but will probably miss the place.
So the best way to get there is by motorbike taxi.
The drivers are all stationed on the other side of the BTS On Nut, at soi 81.
Tell the driver to take you to either "soi 10," or the "Lee Garden" apt condos, where I live.
The cost for the motorbike ride is 15 baht.
When you reach soi 10, there is a 7-Eleven at the corner. From there, its a short walk back to On Nut road.
At On Nut road, start walking back toward Sukhumvit.
Walk about 30 meters, and you will see "One Fine Day" massage parlor on your left.
They open daily, 10 am to 10 pm. (I think Sundays they close about 6 p.m.)
I plan to snap a few pics of "One Fine Day," and the gifted masseuse "Nam," that I can post later.
Sadly, One Fine Day is one of those neighborhood places that doesn't seem to get many customers.
There are only two masseuses, Nam; and her co-worker, Noot, who is very friendly and competent.
One time I came on a Tuesday night, and they complained they had no customers that day.
Feeling pity, I elected for a "two lady" massage: a foot massage by Noot, followed by an oil massage from Nam.
Noot, is single. She is older, maybe 40s, kind of hot small dark body.
Noot seems desperate to hook up. She seems like the kind of unfortunate Thai lady with few options for a secure old age.
Maybe you might be her farang White Knight.
If you are an old, gross, obese and unattractive farang, this might be a good opportunity to hook up with a non-hooker MILF.
It doesn't seem to me like Noot would be too choosy about a BF, as long as you seem decent and sincerely interested in her.
I get the feeling that Noot is not a loose woman, and doesn't do anything much besides being in the massage parlor nearly all her waking hours, so she must be very pent up sexually.
By the way, Nam and Noot do not really know any English.
Unless you know some Thai, there won't be much conversation with them while getting a massage.
It's a shame to me that "Nam" is an undiscovered jewel in Bangkok.
All that lovely wasted talent, mostly just sitting idle 7 days a week.