How tall & wide are you thinking?

For low maintenance, you could look into planting a row of ninebark shrubs. With a variety of foliage colors and mature sizes, you're likely to find something that would fit your taste, and I think their fall color would be beautiful against the blue spruce.

Ninebarks are a good shrub - love them left untrimmed so the branches arc. Mine just started showing the shaggy peeling bark last season, which is an added benefit to the shrub. I'm fonder of the chartreuse of the Dart's Gold than I am of most of the wine colored varieties.

I also like the red twig dogwood, but not sure I'd like to see a whole long row of them in your application. Depending on the amount of space you intend to use, I'd mix it up.

If not considered an invasive in MI, the barberries will give you color - an infill with Crimson Pygmy variety (very inexpensive at Walmart and the big boxes) would give you a good red to coppery green until buried by snow. You couldn't go too wrong with many things with the spruce backdrop.