Really?
If one can't think of things to do in Pattaya, one isn't going to think of things to do anywhere else.
Go window shopping and girl watching in the malls, go to the movies, explore Pattaya on foot, take a bus ride along Sukhumvit- get off anywhere and explore the area, take the ferry to Samet and explore the island, go beachcombing, take up art, take up photography, do martial arts, take a cooking course, visit the local tourist attractions, take the bus to Bkk for a day or two, spend time on a forum, learn to speak Thai, read books, make a model, etc etc etc
Do some good for the less fortunate and become a volunteer at an orphanage or other charity.
OR
sit in your room complaining that there is nothing to do.
Up to you.