If it were just me and one child, most configs are pretty easy.

3-3, I'd normally go with the window because my daughters both like to look out the window, although the aisle is easier for hitting the lav.

On a 3-3-3, I'd personally go middle, just because one of you will always have aisle access. Granted, not window, but priorities, you know? It was especially important to have aisle access when our kids were still in diapers or potty training.