You can always round over the edges of the box. Assuming you will be using trim at the top and bottom, you'll have to mark how far down the sides the top trim will come and how high up the bottom trim will come. You'll need to start and stop your routes there. If you were to route the entire side and then apply the molding, you'd have a funky gap in the corner. Also, if you were to apply the trim first and then try and route, it is much, much harder as the router needs to ride flat across the piece. So layout where your trim goes, round over the corners between the trim, then apply your trim. It will definitely look nice.