Author and master-gardener Melanie J. Watts says in her July 13, 2010 post "Designing a Garden":
To lessen the amount of work or to avoid undoing mistakes it is better to approach garden design slowly, letting it evolve naturally. Take time to see where the sunny spot is in the morning where you drink your coffee and the shade where you escape to on hot afternoons. Notice how the path to the shed takes the quickest route and how the children's ball...always seems to end up in the flowerbeds. Design your garden for the life you have now. You can always make the sandbox into a flowerbed after the children have grown out of it".
Aaaaaaand....exhale. How silly that I was worrying about putting plants in the wrong places rather than enjoying the opportunity to learn and dream now and tinker with design throughout the seasons. I'm in this for the enjoyment, after all. So nice to have been reminded of that!