I vote for the Hydrangea 'Perfection' as it is a macrophylla or big leaf hydrangea and will do better in your shady area than the 'Strawberry Shortcake' which is a hydrangea paniculata and blooms best in full sun in your cool summer climate. You might also consider  the more compact or dwarf 'City Line' series of hydrangeas with names like Rio or Paris as these were bred to grow smaller. You can mix varieties that are the same size but avoid bigger with more compact varieties. Your bed that is 4 feet wide could be a tight fit for some of the larger hydrangeas. In general the bigger the leaf the more shade tolerant the plant and lack of sun is the number reason why the Hydrangea paniculata (with more pointed rather than round blooms) fail to flower.   For some winter color, you may want to plant hellebores at the base of your hydrangea shrubs along with some shade tolerant heucheras and saxifrage. It sounds like the walkway will be lovely. Keep growing, Marianne Binetti