The minivan started from the intersection of South Pattaya Road and Sukhumvit (northbound, next to the gas station and the pedestrian bridge) when I made the trip to Siem Reap through Aranyaprathet one year ago. They have a small office there, everyone will help you when you ask for Aran. The ride was close to six hours as the minivan went through several small towns, but it took you for 300+ Baht directly to the border checkpoint. - The trip was okay, but it was not a VIP bus, just the normal one. - Once you crossed the border, you can take the evening bus to Siem Reap (and take a one dollar win to bring you to a restaurant or cafe to spend the waiting time close to the bus departure point). It is a sleeping bus which I booked online and not too comfortable for my farang size, but good for the distance to Siem Reap. (When arriving there, I had to rush to the driver and remind him to stop and let me out, as he was already through the city center and seemed to forget me ...)