DX to FX
One thing to keep in mind if your shooting architectural and landscapes is the increased depth of field at a given aperture that you get with DX. You will have to stop down more on a full frame camera to get the same depth of field you are used to. For portrait work the advantage is goes to FX but if a deep depth of field is what you are looking for the DX has the advantage. When I got a D600 one of the biggest draw backs for me was the less forgiving depth of field when shooting wide open in low light, but the ISO increase made up for it.
Since you shoot stationary objects the shutter speed doesn't really matter, you are after sharpness, stopping down too much may start to negatively impact your sharpness though.