I visited My Son Sanctuary in July 2016 as a (half) day trip from Hoi An. I had seen the temples at Angkor Wat but my wife and kids didn't see anything similar yet. For them it was the first time to see "this kind" of structures. I arrived before 10AM; allmost no other visitors. I recommend to first walk around to get a good impression and photos without the crowds.
Some part is good preserved but many is destroyed by the American B52 bombing. It was however still possible to see a lot too. I visited with a guide who could explain everything in detail. This really helped allthough normally I visit alone. It's an hour drive from Hoi An and the landscape is totally different: jungle! It's how all of Vietnam once must have looked like.
At certain times there were performances of local dance. Especially for the kids this was very welcome to see after the many brick piles. We had a great time learning about the Champa Kingdom. See some photos on my travelogue.