What's a good translation for 说法？
Yup, in this context, the translation of saying or common saying would work.
Besides the several meanings you pointed out, 说法 also has another meaning that is commonly seen: wording or the way that something is said. An example is:

你刚刚说得有点太复杂，换一种说法意思可能清楚些。
The way you were explaining was a little too complicated, perhaps changing the wording might make it clearer.