Many of Bangkok’s top Sights are located along the Chao Phraya River, as such these highlights can easily be reached using Bangkok’s river bus transport system, while avoiding potential street traffic.

What to Know:

The Chao Phraya Express runs four different lines along the river, orange, yellow, green and red. (The red line is an express route with air conditioned boats). Tickets range in price depending on the line and are single use. Visit: chaophrayaexpressboat.com for the most up to date timetables and line information.
There is also The Chao Phraya Tourist Boat, known as the blue flag route. In addition to single journey tickets, The Chao Phraya Tourist Boat offers a day pass for unlimited transport on the blue flag line. Visit: chaophrayatouristboat.com for the route’s timetables and more information.
There are also private boats for hire and some of the larger hotels have shuttle boats. In addition local ferries located at key piers ferry passengers from one side of the river to the other. One important ferry crossing for sightseeing is the ferry from Tha Tien Pier across the river to Wat Arun Pier.

Here is a simple sketch of the river with the names of the piers to hop off at for the top sights.

What to See:

The Grand Palace 
Tha Chang pier (for the Viseschaisri entrance)

The Grand Palace was the residence of the Kings of Siam (later Thailand) from 1782 until 1925, when they began residing elsewhere; right around the same time that the ‘absolute’ monarchy became a ‘constitutional’ monarchy.  The Palace is still used however for official events and is, of course, a major top sight in Bangkok (also a very crowded one.) The Temple of the Emerald Buddha is also located on the rather extensive grounds of the Palace.

Wat Pho
Tha Tian pier

Just south of the Grand Palace is Wat Pho, probably best known for its very long, reclining, gold, Buddha. 
It is one of the oldest wats (which is a Buddhist monastery or temple) in Bangkok. 

Wat Arun
Wat Arun Pier

Wat Arun, “Temple of Dawn” is located on the other side of the river.  A stunning temple during the day, it’s also a beautiful site when viewed from across the river, all lit up at night. 

Wat Arun is covered with mosaics made from Chinese porcelain.  The story goes that back in the day, Chinese trading ships heading to the Siamese capital used tons of porcelain as ballast, which was then offloaded or dumped into the river on arrival in port, in order to take on the goods they’d come there for.  All this porcelain was used to decorate several temples with mosaics, including Wat Arun.

Flower Market, Pak Khlong Talat 
Yodpiman Pier

Flowers and flowers and flowers – all incredibly inexpensive.  I couldn’t resist buying orchids and roses.  While I couldn’t take them home, of course, I decorated my hotel room with them and as I was traveling elsewhere in Thailand after Bangkok I brought them with me to my next hotel.  At the flower market one can also walk around watching vendors create fantastic flower arrangements with almost unbelievable speed.

The Loy La Long Hotel
Ratchawong Pier

Several boutique hotels are located along the Chao Phraya River… including the Loy La Long, Inn a Day, and the Riva Surya.

View my post: Four Nights at the Loy La Long in Bangkok. 🙂

BTS Skytrain Connection  —  
Sathon pier

Get off at Sathon pier, to catch the BTS Skytrain at Saphan Taksin station.  Sathon pier is also referred to as the Central pier.  Free shuttle boats to the Asiatique and IconSiam malls leave from this pier and you can hire long tail boats from here as well.

Important 
*Remember to drink lots of water.  Bangkok heats up and there may be lines with little to no shade and crowds of people. 
*Most temples and the Grand Palace have a dress code. Shoulders must be covered and shorts or skirts must go below the knees.