If your planters face E, S and W they should have fair amount of sun even with shade cover of the patio provides.
If it's your first year in this house, I'd first study sun pattern there and plant accordinghly.
The easiest way to figure out of how many hours of sun every spot have is to use a 'toothpick' method: every hour, from 8am to 8pm go out and put a toothpick (or any marker) in a sunny area. By the end of the day you'll know how many hours of sun every area receive.
Be aware that amount and intensity of sun now and in a summer would be completely different, therefore you should do that sometime in late May-June, when trees will be in full leaves in your locale.
Size of your planters (8x9") most likely will prevent you from planting anything perennial there as soil there will be completely frozen during the winter and you have to resort to annuals. However you may want to experiment with some spring flowering bulbs (tulips, hyacinths, daffs, etc) and see how it works.
As a blind shot without knowing any particulars I could only venture a guess that for E facing location impatiens, begonias and fuschias could work.

My favorite for continuous bloom are the non-stop begonias The most stunning have been red, pink and, if you can find it,coral. They do well with little sun and like their they name, they perform, non-stop. I interplant with the deep blue-violet torenia.