Bloody hell, Tony just beat me!
I just wanted to say the same, just follow your front wheel along the Eastern Seaboard. Even just south of the concrete Pattaya city it gets nice at Bang Saray and Sathahip, then a bit of mess follows at Rayong but after that its is all nice beaches (some even with hotels) all the way to Had Lek!
The sea-side "behind" Chantaburi is actually amazing beautiful to follow along the sea, but check out the road a bit before as there are some rivers and not much bridges!
The mountain-sides at the other side of Sukhumvit road (after Rayong) are also beautiful and have some amazing twisty good road.
Chang Noi