My first thoughts were rhododendrons or Camellias. Other thoughts for winter interest would be curly willow for it's stems. Maybe Nandina for berries?

-bonnie

I think Taunton yew (Taxus x media 'Tauntonii')looks very nice with red-twigged dogwoods. Keep in mind, to get the best winter color of your dogwoods, you're going to be removing the older stems, keeping the ultimate size smaller than if left to grow "naturally" so you can place the yews in front of or behind the dogwoods, whatever works best for you. I would berm the soil a little, if possible, kind of stages the planting and provides good drainage for evergreens.

Tough broadleaf evergreen PJM rhody
they turn puplish for winter color
green again in the spring, lavender flowers, very early spring

I have a red twig dogwood and old fashion canary weigela. May I suggest that you put them as far apart from each other as possible. With the dogwood, maybe groundcover would be the best bet. My dogwood is over 7 ft and I have to prune every three weeks or less if we have a good rain. The weigela will be the slower grower but I have had to remove a two shrubs and now a groundcover because I failed to realize how wide this thing will get. The reality hit me when I went over to friend. He has a weigela in the middle of his yard. The thing is huge about 6 ft tall and 5 ft wide. A wine and rose should get about 5 ft wide and the same in height. Please keep this in mind when choosing companion plants