We're in the middle of a renovation and I can't make up my mind on which direction to run the tile.

Tile is 10 inch x 40 inch wood look porcelain tile being installed on a slab, so no joists or anything to worry about. We're doing the same tile throughout the house.

I was originally leaning towards side to side because as you walk in the front door, you're walking right into the family room which is wide, however when I think about the kitchen/living room and master/master bath (as well as the hallway back to the other bedrooms), it makes more sense I feel to run it front to back.

Most of the light coming in to the house is coming in from the back - we have walls on the sides of the house that separate us from our neighboring houses.