A little hangout room for your Sims! Can be placed in any park or nature reserve. In my game I placed this room in the Hanford-on-Bagley Nature Reserve :)
Your servants need a proper laundry room. Nice iron pot, a fireplace closeby, dring clothelines. Hamper in the corner - place one of those near the bedrooms in the castle (well in every bedroom is a good idea, actually) and your sims will have nice clean clothing, every day.