Pacific Northwest Gardening: Original garden plan seems iffy now; please help!!, 1 by Tulika

Tulika wrote:
So, just the other day I posted about my viburnums but now I'm seriously beginning to doubt my foundation bed design plan. Attached is a picture of the bed -my front yard is west facing and sloping downward; the planting bed goes all the way down the hill; 18' deep and 16' wide at the very top.

As you can see, there is a huge hydrangea at the bottom of the bed (planted by previous owners). My original plan was to move it back and transplant it in the spot just under the window. The viburnums were supposed to go on either side of the hydrangea. The hydrangea should eventually reach about 5 feet high and the viburnums about 6 feet. I thought I would fill the rest of the space with a mix of purple - blue and pink perennials.

But now I'm beginning to doubt the design... should I use these shrubs or should I get shorter ones so as to not hide a large portion of the brick wall? Also I received some feedback that planting two shrubs of the same kind on either side of a different shrub is not a good design plan. I feel so foolish and confused now!! Please help; any suggestions, whether general design tips or particular plant recommendations would be greatly appreciated.

Please feel free to let me know if neither of these current plants will work for this space. I would like to have at least one hydrangea... but even a smaller one would be fine. Thanks a lot!!