To all you absolute authorities on this subject, appreciate any advice as to the best places in BKK to find sexy lady to take to a resort for say 3/4 days?

That depends on what you're looking for Sun.
If price is your top consideration, try the freelancer places like the Grace Hotel Coffee Shop or Angels Disco inside the Nana Hotel.
If low mileage is more important, try the beer bars on Nana, outside Clinton or next to Cowboy.
Blazers may disagree, but for this type of set-up, I think you could do a lot worse than the girls on Soi 33. Generally they are much lower mileage and are in serious boyfriend hunting mode. Most will jump at the chance to go on a "holiday" with you, hoping to become your gf. And if you don't mind not getting laid the first time you barfine them (be warned, the Soi 33 barfines are steep), they will assume gf status on the second day. You should NOT have to pay them for their time after that.
Of course most of the girls in the beer bars/clubs will do the same thing, but you will get laid the first night also.
I'd estimate that go-go girls probably get fined at least every other day if they are decent looking. Beer bar girls probably 2 or 3 times a week. Soi 33 girls I'd guess maybe once a week unless they are really hot.
Now you could also go for an MP girl, but you are talking the highest mileage and probably the highest cost overall (the mp's don't like to let them go without being paid).
So as any Thai girl worth a damn would say its "Up to you!".

drew

What is a MP girl?
Some of the beer bar girls are semi retired go go girls and not as low mile as one might think

An MP girl is a "massage parlor" girl.