This region broadway covers the plains of Chao Praya river. There is Phetchabun mountain range on the north-east and Tenasserim Hills on the West. The areas focal point is Ayuttaya which the capital city in the past. Following cities are located in the central part of Thailand. 

Ayutthaya — ancient capital built from red brick. Ayuttaya can be visited by riverboat as well as using other public transport. It takes one hour to get from Bangkok to Ayutthaya. 
Bangkok City— Thailand's largest city by far, a sprawling metropolis of wealth, squalor, culture and sin
Hua Hin — Thailand's oldest beach resort. Hua Hin beaches and tourist spots are regulated to provide quality services and experience for the tourist. In the past, Hua Hin has been the summer resort for the royal family. 
Kanchanaburi — the Bridge over the River Kwai, WWII museums and natural scenery
Lopburi — known for it's Khmer temples and crab-eating macaques
Nakhon Pathom — Thailand's oldest city and site of the world's largest stupa
Nonthaburi — the second largest city of Thailand, actually a suburb of Bangkok
Phetchaburi — known for the Khao Wang mountain and access to national parks
Samut Songkhram — an interesting village with the Mae Khlong Market and nearby floating markets


There is plenty to see in the central region of Bangkok. You can explore more by reading about Bangkok. Most places around Bangkok are accessible by land sea and waterways. The old city of Ayuthya is accessible by charter boats and makes a good day trip for people who want to explore the rich history of the region. 

Samut Prakan has interesting museums or you can ride on a bot to explore Nonthaburi and Ko Kret.

Some ideas for day trips in the central region are:

1. Drive up north to explore the beautiful city of Ayutthaya

2. Lop Buri

3. Driving southwards you can stay in the beautiful sea resorts in Hua Hin, Cha Am and Ban Krut

4. On the Western side, you can explore River Kwai Valleys. Kanchanaburi is a popular destination with tourists. You can take a couple of hours of bus ride to Pagodas Pass to the border with Myanmar.