Here are some suggestions:

The main ground ( sa-naam+ luang+ and the nearby area)

1. The Grand Palace.

	There are different types of architectures and structures in the 
Grand Palace ranging from the Dusit Hall which is a pure Thai castle to
the Jakri Hall which is in half Thai half western style, the Dhebidorn Hall 
which is influenced by Khom's arts,  and the Chinese Garden which is 
influenced by the Chinese culture. ( Most of the construction were built in 
the reign of King Rama I upto King Rama V)

	You can also visit the Emerald Budha Temple which is the only 
temple inside the palace.  Inside the temple and on the corridor's wall 
around the temple, you can see the Thai mural paintings and pearl-in- laid 
door which is a kind of popular fine arts in the early Ratanakosin period.

	The entrance fee is around US$ 4 for the non-residence of 
Thailand. The ticket also includes the fee for entering the Wimanmeek 
Hall which is a museum for the gifts that the royal family received from 
abroad.

2. Wat Prachetuphonwimonmangklararaam (Wat^ phoo-)

	Wat pho was built in the reign of King Rama III and is admired for 
its architecture which is called yoo"mum- maay^ sib' sOOng+. Every 
structure in this temple was built in square form with 12 angles  There is 
also a big statue of the reclining Budha image inside the temple.

	Admission: less than 50 baht.

3. The National Museum

	The National Museum is situated in one part of the Palace (wang-
lang+) A lot of Thai arts are on displayed there.

	Admission fee is required.

4. The National theatre.

	The National theatre was built around 50 years ago. It is a kind of
mixed structure between western arts and Thai arts.

5. Rachadumnern Avenue

	This avenue is one of the best designed avenue in Thailand. All the 
buildings on this Avenue are built in the same style. Some people 
mentioned that it is an imitation of Champ Elise in Paris.

6. The Golden Pagoda

	The Golden Pagoda is in Wat Sra'ket' which is at the entrance of the 
Rachadamnern Avenue. The golden pagoda was built on the man made 
mountain and can be clearly seen from distance. You can climb up to the 
top and see the bird eye view of Bangkok.

7. The Metal castle.

	The Metal Castle or loo-ha'praa-saat' is in the Rachanadda Temple 
near Wat Sraket. It is the replica of the Lohaprasaat that Nang Visakha 
built to honour Lord Budha in India. There are only three of its kind in 
the world: in India, Sri Langa and Thailand.

Amporn Garden Area.

1. Anantasamakom Hall.

	Anantasamakom Hall was built in the reign of King Rama the fifth. 
It was built with  the marble from Italy. The architecture is in 
Renaissance style. It was once used as the Thai Parliament.

2. The Marble Temple.

	The Marble Temple or Wat Benjamarachabopit was also built in 
the reign of King Rama V. The architect is Prince Narisaranuwatiwong 
who was the great architect at that time. The Marble Temple is admired 
as the best designed temple in Ratansakosin period.

	There are a lot of Budha images from different period around the 
Temple corridor. The reflection of religious belief in each period of Thai 
history depicted in these images are worth noticing.

3.Wimarnmeek Hall.

	Wimarnmeek Hall was once the summer palace of King Rama V 
and now was turned into the museum by the kindness of the present 
Queen. The Hall is a  three storey building situated in a pond. English 
guide tour is provided everyday.

4. Pitsanuloke Estate

	This estate was built in the reign of King Rama VI in the western 
style.

The Ancient City

	If you have not much time to visit the important places around 
the country, you can go to one place and see it all. The ancient city is the 
biggest outdoor museum in Thailand. It is in Samutprakarn, the nearby 
province. The replicas of all important places  in Thailand are displayed 
there [...] ranging from the temple in the northern part of Thailand, the
stupa from the South, the Cambodian style castle, the palace both from the
Thonburi and Ratansakosin period and the Thai style house. The admission
is US$ 2 dollar for one person or US$ 8 for the whole car.

Have fun with your travel in Thailand.