AE question: easiest way to make a group of objects move in a dynamic / fluid motion

I'd like to move a group of layers/objects across a map fluidly/dynamically and I'm not sure whether to parent them to another shape layer or null so that the master shape layer or null pulls them across. But what I'd like to do is have the squares (in this example) move fluidly in the sense that they don't all take off and stop at once. I know I should use easy ease keyframes and perhaps stagger the 'square' layers. But I was wondering if there might be a better way to do this with expressions or a plugin perhaps? Thank you in advance for any helpful tips / suggestions.