Straw piles are always fun - when it's cold they snuggle into it (otherwise they do flatten it down). A sandy area for dust bathing is always appreciated. If you make a hidey house the hens will generally lay in there. Lots of plants and wood (to climb on) to break up their lines of site will make for a peaceful group.
Add some sticks... maybe a rock? My pet coturnix love this rock I put in their hutch. Especially the male! He likes to sit on it and crow to all his lady friends. Lol