Ilex crenata 'Sky Pencil' is an obvious choice.....IME, it makes a great container plant. Other possible choices would include Euonymus japonicus 'Green Spire', dwarf Alberta spruce or lemon-lime cypress (Cupressus macrocarpa 'Wilma Goldcrest') although that may be of marginal hardiness in your climate. And might lose its coloring if not in enough sun.

I’m not clear about what problem you’re solving. If that was my deck, I’d start with a small table on the left under the lamp—allows you to put a tray of drinks or whatever down while you open and close the door.

Shrubs—hollies and yews, if you are all in for traditional and evergreen. Since the door and deck are not symmetrical, I would not go with a matched pair. (Beware of the dreaded funeral home entry look.) If the back of the house simply looks bare to you, consider a cover over the door and plantings (especially an ornamental tree to help establish a partial overhead plane) around the deck.

Back to pots. Mixed pots with annuals, perennials and something evergreen would be fun to play with. Large pots with bubblers bring water and wildlife. Vines in pots can provide height, and there are beautiful options for small frames they can climb up.

If I were to plant an ornamental tree in front of the deck ( to the right of the stairs leading to the lawn), how far away from the deck should I plant it? I like the idea of a tree.

Depends on how big the kind of tree chosen grows.

Agree with comment about house design ruling against an identical pair of potted shrubs. Also vertical looking ones would emphasize height of house and shapes of windows, rather than softening them.

OK - no I have nixed the idea of two containers alongside the slider doors. Now I am thinking of just one substancial container planting on the right hand side only (when facing the house). There I will have room for something a bit wider.

Cor, With that type of lighting Japanese Maples should work well there.