Nang Ram Beach is 45 minutes away from Pattaya by driving. It is situated in the Royal Thai Navy land but is open for public and is free as I remember. The place is not congested and is less touristy. Beach chairs can be rented out. You can also buy food there BUT with limited options so better bring your own food. There is ample parking.
The beach is clean and the water is clear. It is also lined with beautiful pine trees. I'm sorry to say that you have to drive yourself to get to the beach or maybe arrange a taxi to and fro from your accommodation.
For driving directions, please go to this link - http://www.traveltosiam.com/Sightseeing-Chonburi-Haad-Nang-Ram.html