Post this on Home Decorating and Design, with a little more information about what colors you like and some close up pictures if you have them.

I would go with some soft color instead yellow.

One thing I like about the planter is it gives a long, level baseline for plants, rather than your slope. I'd try to keep it, or reconstruct something similar. It doesn't look like you have enough width there to do shrubs, so plant it with soft/easy perennials like the decorative switchgrasses (the shorter ones, not the taller varieties), rudbeckia, shorter goldenrods, etc. Cut them all to the ground in spring just before growing season -- simple. The shrubs along the side of the drive look like they might be nice to keep, just need a little weeding. I don't know about adding a fence behind them. If you keep most of them a fence would not be visually necessary. I like a nice generous landing. Could yours be extended out along the house, maybe to just beyond the first set of windows? Looks like you can't go out into the drive much, or you'd interfere with cars using the garage. For paint colors, I like a nice bright front door. Just about any color would work for yours. I also like it when the garage doors and side doors are painted to blend in rather than stand out. So I'd choose a medium tan-ish color. Again, let the front door be the thing that draws the eye, not the garage doors or side door.

The concrete planter around your tree is an interesting (and assumedly original?) feature, but nothing else in your landscape “talks” to it so to speak. With midcentury homes I think ‘poured-in-place’ concrete always looks good— it’s not that different from your paver idea, just at a more appropriate scale & function. Here’s a really bad rendering done with a fat thumb on my phone, but the gist would be to have larger rectangular concrete sections (could be gravel or grass in between) that abut your concrete planter, and having those surrounded by some nice native grasses with a another planted section in the middle, and then echo those same plants in your raised concrete planter around tree). Neat house!