One of our greatest joys was catching the Chao Praya river ferries to various temples and palaces around the city. When the temperatures were nudging 40 degrees Celsius it really was one of the coolest ways to get around - as long as you didn't have to wait in the sun on the dock too long for a boat to come!
There are a couple of different ways to get up and down the river. You can hire your own long-tail boat (most expensive). get an all day ticket for tourists (next expensive), ride the tourist boat (second cheapest) or catch the regular local ferries (cheapest).
We found that the price of the tourist boat (40 Bahts) compared to the regular local ferry (15 Bahts) was so insignificant that we often ended up catchin the tourist boat. They seemed to be less crowded and run more frequently.
After a couple of times not being able to get on to a local ferry after waiting for 30 minutes in the scorching sun we stopped using them!
Monks are everywhere in Thailand and they always give off such a sense of serenity.It was nice to be able to place two iconic symbols of Bangkok in the same image.