Bangkok is Thailand’s capital, a large city with more than 8 millions of people. Bangkok is also called "The City of Angels", Krung Thep, a short version of the official Thai name of Krung Thep Maha Nakhon which is an abbreviation of the full ceremonial name which is also the longest place name in the world:
Krung Thep Maha Nakorn Arun Rattanakosin Mahinthara Ayutthaya Mahidol Pop Noppharat Ratchathani Burirom Udomratchawiwet Makhasathan Amon Phiman Awatan Sathit Sakkathattiya Witsanukam Prasit
A general translation of this name is: "The great city of angels, it’s where the immortal divinity dwells, the invincible city, the royal capital endowed with nine precious jewels and full of joy, it is abundant with enormous royal palaces, it’s where the reincarnated angels reside, at the order of Inrda, Vishvakarma majestically built the capital"
But Bangkok is also known for its ornate shrines, big temples and vibrant street life (by day as by night). There are lots of interesting places to visit like the Grand Palace and its sacred Wat Phra Kaew Temple, Wat Pho Temple with an enormous reclining Buddha and, on the opposite shore, Wat Arun Temple with its steep steps and Khmer-style spire. Without forgetting the floating market.
If you can, I really recommend to spend few days in Bangkok before or after being in Koh Chang. You cannot come to Thailand without visiting Bangkok at least one time. You can visit it by yourself or take a guide with you, you won't loose time to find your way if it's the first time you come to Bangkok. Be careful, some guides will bring you to places forcing you to buy something (jewelries, statutes, suits) in order to get a commission. I recommend you Ing Taxi, with his team they will bring you where you want and you won't be scared to be scammed, they are very serious and safe. More information here or on www.ingtaxi.com.
There are lots of hotels where to stay in Bangkok which makes the choice very difficult. Here are some of the best daily deals you can find: