When we speak of pleasure we speak of agreeableness, but exactly what kind of agreeableness is going to be personal to the individual living thing that is experiencing it. There are no Platonic ideals in any other aspect of life, and I don't think there is a Platonic ideal of "the highest pleasure" that fits everyone exactly the same way. Pleasure is ultimately a feeling and feelings aren't abstractions that can be stated in a precise mathematical or verbal formula. To employ one of the phrases we posted about recently: All models are 'wrong,' in that they are not the exact equivalent of the reality that they seek to describe, but some models (like "absence of pain") are useful, in that they help us understand how to target a goal.
Here is a possible example of a situation:
Let's say a person goes to the grocery store to buy some eggs (healthy and easy to make) and also sees a nice looking big bag of Easter candy chocolate eggs, and brings that home too. After eating a nice omlet for dinner he feels satisfied, but an hour later he then opens the bag of chocolate eggs and eats them even though he is not hungry. He enjoys them because the sweet taste is very enjoyable as he is eating them. In fact he often buys candy or chocolate and feels compelled and driven to eat it whenever there is a dull or boring moment, such that he has developed "a sweet tooth habit" and is also over-weight and is pre-diabetic. Even when he is not hungry he thinks of chocolate (a feeling of restlessness comes up). When the bag of candy is in the house it is almost impossible to not eat it and it doesn't last very long before it is all gone.
I would like to propose that by thinking through the idea that "the highest pleasure is the absense of pain" will provide some insight into the sense of discontent that is at play in this situation and provide an opportunity to develop contentment rather than be driven by compulsion. And the factor that most determines the outcome is to not buy the candy at the store. So this is an example of using this idea as a therapeutic tool.