Bang Sue Grand Station is the largest railway station in South-East Asia. First open on 1st August 2021, as of 2022 there are only limited trains departing from this massive complex as trial runs before most of the regional train services are migrated to this station from the old Bangkok Railway Station (Hua Lamphong). It will take several years before this becomes the major Grand Central Station of Bangkok.
As of 2022, you can get a train from Bang Sue Grand Station to Chiang Mai, Ubon Ratchathani, Nong Khai, Den Chai as well as a regular service to Don Muang Airport.
One of the first high speed railway services that will leave from Bang Sue to Hua Hin is in the planning. The feasability study to build this high speed railway line will end in August 2022. With a maximum speed of 250Km/h will see a train from Bangkok to Hue Hin take around 1 hour. Currently the train from Bangkok Railway Station Hua Lamphong takes more than 4 hours. You can get a mini-bus in 2.5 hours.
When I visited in August 2022 I did not see any food shops in Bang Sue Station. There are many sections of the Grand Station which are closed. There are escalators that go up but they were closed. I presume when more trains are leaving from Bang Sue Grand Station, all the usual suspects will open here like McDonald’s, Burger King and Starbucks. There are a few vendine machines scattered through the concourse hallways of Bang Sue, including a few at the main entrance.
You can get to Bang Sue Grand Station on the MRT underground subway. I traveled from Sukhumvit Station to Bang Sue, a total of 11 stops costing 40 Baht. Bang Sue is just a few stops away from Chatachuk. The MRT station is located directly below Bang Sue Grand Station with a long trip up the escalators and along a long tunnel to get to the departure area.