Every sub-panel that I have installed has been located in a location where I have the shortest homeruns to my major appliances (water heaters, furnance, a/c, dryer, etc). I have put them in the walkin attic located off the 2nd floor, attached garages, and laundry rooms. It's a lot easyer to run (1) big romex to supply power to your sub-panel vs. multiple home-runs to these appliances from your distribution panel.