I'm a sucker for evergreens, and think they should be used whenever possible in this climate, it makes your garden so much more attractive during the off-season. For a foundation planting you may consider mountain laurels, Kalmia latifolia. There are a great many variants that have beautiful blooms and are a nice leafy evergreen. Another evergreen flowering foundation planting could be Polemonium caeruleum ÂSnow and SapphireÂ.

For the second spot you may look into some dwarf camellias. They are slow to grow, but like shade, and bloom in late fall or early spring, sometimes in the dead of winter. I believe what you'd be looking for is Camellia Japonica. If you love fragrant plants, you may also consider daisy gardenias. They prefer more sun I think, but do ok in partial shade.

Don't put matching pairs at the door unless you have a geometrically symmetrical house facade - with an accompanying formal garden layout. Achieve balance instead by using different kinds of plants on each side that have similar total volume, for example a small shrub + a medium shrub on one side and a large shrub on the other.

Daphne odora 'Aureomarginata' works well beneath taller broadleaf evergreens such as hybrid rhododendrons near a door or path so you can smell its uniquely scented flowers but the shrub does not appear as a solitary specimen, a use for which its somewhat undignified growth habit is not very suitable.

As the Katsura tree grows it is likely to suppress underplantings. Maybe Mahonia aquifolium 'Compacta' would tolerate the conditions and look well with the Vacciniums.