Aucuba Goldstrike, Azeleas,either Dwarf Gumpos or Encores, several species of Hollies like shade, Fatsia Japonica do well but, will require prunning else, they get rather large. Why not mix it up a bit?

Hollies are always good for low maintenance, if you don't mind the pokies. The glossy leaves might be a nice contrast to the brick too. I like your idea of the trailing gardenia too. Pretty white while adding fragrance.

vroomp -- True...gumpo azaleas would be good (forgot about them) and now that you mention it, maybe Carissa holly could work...although it does get a little bit wide and those planters (I should've mentioned this earlier, but I just went by this afternoon and measured) are only 2-feet wide.