Siam Square is a meeting place for high school students, university students, and also office workers. It is a big shopping area in Bangkok. Within this area, there are many shops, bookstores, restaurants, coffee café, clothing & accessories shops, and so on. Besides, there are several shopping malls around the area such as Siam Paragon, Siam Square One, Siam Center, Siam Discovery, and MBK Center.
Asiatique The Riverfront is a lifestyle shopping center that is located on the Chao Phraya River bank. Many locals love to go there in the late afternoon or evening. It is one of the great chill out places in Bangkok.
If you are tourist and you want to visit both Siam Square and Asiatique, you can do it within one day. I recommend you to go to Siam Square first, and then go to Asiatique in the evening.
To go to Asiatique from Siam Square, you can go by taxi, bus, and BTS Skytrain plus boat. I recommend you to take BTS Skytrain and boat in order to avoid traffic jams. Besides, the view on the boat to Asiatique is also nice.
From Siam Square, you get on the BTS Skytrain and choose Silom Line. Then, get off at Saphan Taksin BTS station which is the station that connects to Sathorn Pier. You can take Asiatique’s service boat from there. It is free. This service is available only from 16.00-23.30.
Hope the information helps.