Answer: Semi-evergreen in your area means in most winters they will defoliate, or in a very mild year the leaves may simply hang limply in place and look a bit (to my eye) sad. In my own zone 6 garden for example, the Burkwood leaves usually hang on until December or so, then drop. It is a matter of personal taste if you would like that in the foundation area, or not -- The plants themselves are all very nice plants.
For a more static look you might consider smaller varieties of catawba rhododendron (this is a large plant so smaller in this case actually means in the five to seven foot range) if you want a flowering plant, a small textured braod leaf such as the hollies, or a needled evergreen such as yew. These will not grow as quickly as deciduous plants would, but they will be evergreen all winter for you. I would probably not suggest boxwood because it tends to be very slow growing.
To some extent the selection would best depend on the growing conditions in the location you want to fill. Your local nursery personnel and local County Extension might also have some suggestions based on more precise information about the exposure to sun and wind, soil type, typical soil moisture, microclimate in your yard, and so on. I hope this helps you begin to narrow things down.
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