EPIPHANY - Back Yard Priority

The other week, sitting in the back yard with my sister who was visiting from Victoria BC, it suddenly became clear to me that I needed to switch my attention to the back yard, after all we were spending a lot of time there once the dwindling daylight forces us to shelve our gardening tools for the evening.
My sister brought fresh eyes with her and because she did not know that the backyard did not have the same priority for me as my other gardens, she suggested moving the gorgeous Calla Lilies from the front into the back where they could have a highly visible place of honour, right beside the seating area.  I never would have thought of it but they look smashing, holding court between the two trellis.
Prior to this moment almost all of my planning has focused on the front and side yards: the Sun, Moon & Monet gardens I have been so busy writing about. In fact readers of this blog might wonder if I even had a  backyard!
The plan for the backyard garden is to have no plan.  To move plants here when there is no room for them anymore in their original bed, to put gifts from friends that do not work in my other gardens and to incorporate the daylilies, Asiatic Lilies, and chives that were already so plentiful here.
Given the symmetry of the trellis and windows I have so far been repeating plants in a balanced way, however I am wondering if I should not just go wild and abandon principles of balance in both color and form and see what appears. ..it could be a very interesting learning experience. Can I 'let go' after so carefully planning the other gardens? A place to put plants that are not working where I had initially hoped they would thrive could come in handy, and undoubtedly I would learn from seeing combinations that I would not otherwise have planned.
Let me know what you think, do you have a bed for mismatched plants from tests, gifts or overflow?  Do you ever stop and think how well it is working, or does it always look like an "unmade bed" to you?