Hat Yai Observatory sits in the hills of Hat Yai Municipal Park, giving it a practical advantage before you even get to the astronomy: the outlook over the city and surrounding plain is broad and easy to combine with the park's other viewpoints and shrines.
The observatory is a modest science stop rather than a major attraction, but it gives families and curious travelers another reason to linger in the park. Clear evenings are the best time to aim for if public viewing or sky programs are running.