Hydrangea macrophylla 'Blue Danube' easy to grow, will grow in sun or shade, and in most different types of soil. Although, remember that an acidic soil will give blue flowers, whereas an alkaline soil will produce pink blooms!
Purchase an end cap, fill with rock, soil, and plant. You can put these in the center of a very large pot to stabilize, and add amazing height and color to a container that has trailing plants (no end cap or rock needed if you are placing in a container)
Hydrangea macrophylla 'Dolce Kiss' has brooding dark leaves and bears lacecap heads of white flowers edged pink. Almost certainly bred from and is definitely a bigger version of Hydrangea serrata 'Kiyosumi'.