Hi Harvey and welcome. If you take a look at some of the threads in the newbie's area you'll find alot of info about most things you want to know... I have been to Patong once a few years ago but I'll be going again thou under different circumstance s
About your question, a bargirl cost about 300-500 baht to barfine and additional 1000 baht you'll have to pay to her. A gogo girl cost about 500-700 to barfine and additional 2000 baht for her services... This prices are for long time which means over the night, cheaper if you want her for short time which would be about 3 hours or so.
As far as I know there are less girls during low season but also less farangs and still plenty of girls, so not to worry about it. The month with most rainy days is october I think.
Have a great time!
