If you have stayed in Pattaya for long years or will stay long from now on in Pattaya, I will recommend “Universe gym” for your best gym in Pattaya.
The gym had been located at Sukhumvit Road side, but it has been moved and renewed in 2016. Now the gym is located near Pattaya Klan (Central) Road, and also reaches from Sukhumvet road through Index (Furniture shop).
At present the gym has the best balance between price and facility quality. The price is cheaper than other good gym such as Fitness 7. And they have enough parking spaces for motorbike and car for free in from of the gym.
So if you want to visit gym frequently for long years, the Universe gym is the best gym I recommend.