A few notes: The new train station is huge and much underutilized. Must be planning for a lot of future rail traffic, or high-speed rail from China. Labour costs are high enough that the left luggage facilities (lockers) are automated. Had difficulty using them and would suggest not using them unless one had a lot of time to figure out how to retrieve bags. All departures (and food stalls) are at the north end of the station so at the other side of the station from the underground transit.

Had one of those old 2nd class sleepers to Padang Besar with open-window (and thus very hot/noisy) dining car at the end. Smarter option would have been to order food from the staff that come around. Train got hung up around Hua Hin and was over 1/2 hr late at one time but even with pfaffing around shunting cars in Hat Yai, got into Padang Besar maybe 10-15 minutes late so plenty of time to go through the 2 sets of passport control + Malaysia customs and more than enough time to get KTM tickets and something to eat.

Sleeper cars were pretty much full out of Bangkok but gradually emptied out along the way with most getting off before or at Hat Yai.