how about some type of container garden?

Full sun and shade? Sorry if I sound confused ;)
Mailbox planting can be a touchy subject. I know most people want something bright & constantly blooming, but postal workers might be happier dealing with little to no wasps & bees.
Pansies? Generally I don't grow them, but, did decide to do 2 hanging windowboxes on my front railings. Well, they died off already, and there's no sign of them coming back. So, you're not the only one that has problems with those, LOL! I'd love to say sedum, if the bed is indeed full sun, but they're wasp/bee magnets, which I love (well, no so much the wasps). I have loads of sedum, just about in every bed in my garden. Plus, I leave them up all winter; I love the look of the dead blooms poking up through the snow. They're happier when neglected. Daylilies fit that bill too. Rudbeckia & echinacea, again, bee magnets, but goldfinches love them too.
Some Arum italicum would provide pretty winter foliage, but during their bloom time, the berry stalks they produce are nothing to look, so that's one plant to rule out looking nice during the summer, since the foliage disappears.
I could ramble all day long, sorry!

When you say full sun & shade does this mean it gets morning full sun and afternoon shade or morning shade and afternoon full sun. This can make a difference because generally morning sun is gentler and afternoon sun is stronger.

In the corner, but the wall, I would plant a skinnier, slowgrowing evergreen to add height and interest. Around the mailbox, grow a vine such as clematis - pick one that blooms all season. Some clematis only bloom in the spring. You could edge the front with a variagated lirope. It looks kind of like a pretty grass but it does have purple flower spikes too. In between the lirope and the evergreen (dwarf alberta spruce comes to mind as a suggestion) you could plant a medium height plant. Pick a color scheme and plant accordingly. Black eyed susans or stella d'oro if you want yellow, veronicas, catmint, or purple coneflowers for blue/purple, shasta daisies for white, guara, strawberry candy daylily or geranium "rozanne" (the perennial kind of geranium) for pinks/reds/violet. You could subsitute flowers for interesting & colorful leaves with Heucheras that have reddish/purple tints or hostas with white/green/yellow and/or blue colorings. Only plant heucheras and hostas if you have morning sun in this patch. Afternoon sun will bleach the leaves.

Hope this gives some ideas. I picked fairly common plants that you should be able to easily find at a nursery that have a long season of interest. You may see something else that strikes your eye when you go shopping.

Pansies do well in cool weather and will often die in the heat of the summer.

I notice that your siding goes right down to soil level. Are your foundation sill plates nearly at soil level too? If so watch out for termites and rot under the siding

Looking at the picture it appears that the area is quite small. Not sure of your budget, but I would suggest hellebores (for color and flowers in early Spring - March to June) with some annuals (Wave Petunias, perhaps for color until frost). Some hellebores are evergreen and some flower as early as Dec. You could add lillies (perennial) if you wish

Phlox paniculata do very well for me. There was a pause in flowering and dieback and some dead stems when we had the recent hot dry spell but the flowering has now resumed and I just cut back the brown stems. They reseed for me and are nicely fragrant too. They do start popping up in the middle of other plants so I have them mixed up with daylilies

Here is a link that might be useful: My flowers after June 1