. I'm hesitant with Windermere in the centre because it is just too unpretending. My "view" is something very bold that will stand out and give character to the full group or on the contrary something relatively large but white so that it will break the possible excessive symetry. Do you grow Buddleya davidii there? There are white forms that might play that role. Also some of the Spiraeas. Please understand that my proposals are almost wild guesses because I really have very little understanding of your ultimate goals. Colour also is something related to the quality of light there. We both live aproximately at the same latitude south ( you at 41º 33 and me 41º 13), so therefore we enjoy long side lighting in relatively long sunsets and sunrises. This has great impact of how colour is seen. I don't know how bright are your skies in the growing season. Ours are very much so, so searching for a subdued pastel colouring is almost impossible for me, with most of rains concentrated now and later in early spring. But reading your average weather data you seem to have overcast weather in summer too, so my consideration might not apply there. Thus I indulge in bold colouring freely and keep away from pastel colouring (in spite on my great propension...
) in the summer garden.
I keep thinking .... alternatively from above, what about a tall growing D.A in the center boldly orange, but with old garden rose character i.e Grace/ Lady E Hamilton/ Crown Princess Marghareta or even Abraham Darby? These all will tend to merge JC and Boscobel into a warm center mellowing the ends with cooler soft pinks with SA on one end Ambridge the other.
Some of the many other species of Foxglove (Digitalis) could be an alternative, but I don't know what is available there. Common garden foxglove has been naturalized here and grows under our Southern beech forests (Nothofagus) which I know also grow in your state but I really wouldn't know which would not be invasive there. i.e Digitalis ferruginea
Yes, when you are not looking out for anything in particular the right plant pops to your sight!
I wish you good luck in that sense