I do not recommend roses in partial shade but Japanese holly, or Osmanthus would be a great shrub for both the full sun and the part shade areas. Any native or English holly would grow too large for the space. An evergreen such as euonymus fortune or winter creeper will also fill in despite sun or shade and not grow too tall or need more root room. If you want color add spring bulbs such as daffodils and tulips or summer bulbs such as lilies and dahlias  keeping in mind that the bloomers will do best in the sunny part of the container as you learned with the lavender. For color in the shade add perennials like hosta and saxifrage or annuals like impatiens and lobelia. The more different plants the more casual look but for a formal appearance limit the variety of plant material. One more idea - I notice your bright yellow scooter. There is a shrub with bright yellow and orange  foliage called spiraea 'magic carpet' that will do well in sun or part shade and the foliage color is highlighted but summer blooms in pink. As fun and loud as the scooter. Keep growing, Marianne Binetti