Are you looking to go to Pattaya from Khao San Road ?
The name Pattaya evolved from the march of Phraya Tak (later King Taksin ) and his army from Ayutthaya to Chantaburi which took place before the fall of the former capital to Burmese invaders in 1767.
When his army arrived in the vicinity of what is now Pattaya, PhrayaTak encountered the troops of a local leader named Nai Klom, who tried to intercept him. When the two met face to face, Nai Klom was impressed by Phraya Tak's dignified manner and his army's strict discipline. He surrendered without a fight and joined his forces. The place the armies confronted each other was thereafter known as "Thap Phraya", which means the "army of the Phraya". This later became Pattaya, the name of the wind blowing from the south-west to the north-east at the beginning of the rainy season.
Pattaya was a fishing village until the 1960s. Then, during the Vietnam War American servicemen stationed at nearby U Taphao or other US bases in Thailand began visiting Pattaya. One story, unverified by a reliable source, notes that it all started when a group of 500 American soldiers stationed at the military base in Korat were driven to Pattaya on 29 June 1959 for a week of rest and relaxation. They rented several houses at the south end of the beach from a prominent Thai, Lord Sunthorn. Despite their short stay, the soldiers had a great time and raved about the place. The word spread among other American soldiers stationed in the region and Pattaya quickly became a hot alternative to Bangkok.
Credit to Wiki
If you ate in Bangkok you have at least 2 choices to go to Pattaya
You can leave from Ekamai if you're in the Sukhumvit area, or (from Southern bus terminal the other side of the river, especially if you are in the Khao san area) also known as Sai tai Mai.
Only 108 baht. $3usa.
Then you can take songthaow, shared, to your hotel 50 baht..Jomtien will be more.