There are some greating pickings at lunchtime around Nana and with a great ST Hotel availble in Nana Plaza (third floor) you really cant go wrong!
Try 'Morining to Nite' - some very pretty girls here or 'Charming Bar' which has the added bonus of a ST room on site.
Loilita's on Asoke is another option and I have found here that the gilrs are more than willing to step out to a ST hotel (Asoke Place) for some non bj fun!
I have always found pretty scant pickings at the Beirgarden soi 7 at lunchtime altough maybe I was just unlucky. This place has the bonus of no bar fines of course.