We booked a van from Bangkok to Prachuapkirikhan. We arrived an hour early and found Platform 9 at the bus station quite easily. However it's among an area where a lot of other transportation booths are set up with vendors vying for your attention. We showed someone our confirmation on our phone, and were given tickets, then directed to wait nearby. Then someone signaled us into a van that was already loaded with a few people. The van was pretty cramped, not much space nor was there a trunk. We had to keep our large backpacks with us so we were even more cramped. When you purchase your ticket online you'll get a confirmation after your purchase which states in fine print that you need to pay for an extra seat if you have big luggage. Luckily nobody charged us extra for bags, but we did have to deal with being cramped with our backpacks piled on top of us. The van waited to fill up a bit more and departed about 45 minutes earlier than schedule. We went from Bangkok to Prachuapkirikhan, and it took us about 5 hours. The van stopped along the way to let off passengers and pick up new ones. Aircon worked pretty well, Thai music played the entire way. We had a short bathroom break about halfway through the ride. Don't linger around because the driver may get impatient (ours did when a couple people took extra time to buy snacks). By the time we reached Prachuap, we were let off at a bus station about 3 kilometers from the center. There were no taxis nor tuk tuks around. When we inquired inside about taxi, we were given a pretty expensive quote so we walked instead of paying a large fee. Overall the ride was ok but you really should know before hand where you'll get dropped off. In case you end up somewhere without taxi, which I've read in other reviews.