Raid your sister's closet unless you do lots of formal things at home is my suggestion. Who knows, you might even want to eat "in" one of those nights. I had a feeling it would be three. That is the norm for 14 day European. I find that my "formal" outfits take up less or same packing bulk. I mix match tops and bottoms with all levels of dress, so it is not a problem to me what they require. I always overpack anyway! To me, if it is all checked anyway, what's the difference?