We didn't stay at the Marriott in Hua Hin but did recently stay at the Hyatt and can answer a few questions. The Marriott is about a 10-15 minute walk to downtown (much closer than the Hyatt). It takes 2.5 to 3 hours to get to Hua Hin from BKK. I don't think that the Marriott would have any type of shuttle, but there are several car service agencies in BKK that will take you there for approx $50 depending on the type of car you want. You can also book ahead online, which is what we did. We used Ken Diamond Tours. We had the same driver both ways - he was on time and a good driver.