The original forced air furnace installed in my century old house had central heat registers in floors and ceilings and they didn't work worth a darn! They seemed to produce nothing but cold drafts near all the exterior walls and windows.
When we installed our new, more efficient forced air system, we tore out and replaced all the original duct work. We put the registers underneath (1st floor) or over (2nd floor) each window for the same reasons you are facing. The secret (to the ceiling registers especially) was to make sure there was a cold air return on the direct opposite side of EACH room. If the incoming heat is FROM A CEILING register, it is particularly key that the cold air return vent is placed NEAR THE FLOOR on the opposite side of the room. That pulls the heat down and across the room.
I live in the Land of Oz, and we get mighty cold here in the winter and mighty hot in the summer, so I feel confident that this system should work just as well for you no matter where you live or what season it is.