I would keep the planters and add an ornamental tree to each one. The front small rectangle, place the tree in the right half and in the planter behind it, plant the tree to the left. In the larger planter plant the tree toward the front. Then mass each of the planters with a few low growing bushes, perennials and some ground cover.



I would think about painting the trim of your house white and the vestibule area white, too. It seems dark.

I like the images posted by haussaon - they give good ideas for different heights and shapes, which I think is your biggest need. Looks like you already have rosemary or lavender, which will grow bushy and have a medium height. Ornamental grass would also be nice in the mid-height range.

Maybe a few low plants on the edges with different textures - chicks & hens, mountain pinks (a low phlox).

Then the higher plants/trees: it does seem like you need one item in each of the 2 lower planters to break up the span from street to house. If you want your house to peek out, the ornamental idea is nice. Or you can go taller in the planter closer to the house, with a juniper spire or one of those space needle (?) hollies. Or a tall grass (eg pampas?).

Along the house and by your front door, I love rosemary... doesn't take up too much room but looks lush and you can pop out and clip some year-round when you're cooking...

For me, I don't think there is enough contrast between the stone beds and the pathways. I would get perhaps slate or other large, dark smooth stones (as below) to pave the paths, which simplifies the visual.

The three beds just above here would make more of a statement if they were different levels, either of the bed or plant material (easier). In either case, a mass planting of one item per bed is going to look much cleaner. I agree with sstarr93 re. the paths. On the steps,a more sculpted vertical would be in keeping with the modernism you are looking for.
http://4.bp.blogspot.com/-j2WIPDBX_lU/TlEZvBt453I/AAAAAAAAWbc/B6kZVEm_SBE/s1600/Screen%2Bshot%2B2011-08-21%2Bat%2B10.43.14%2BAM.jpg

For starters I would remove the 2 planters (everything ) to the right of the long one. Replace with grass. Create a plant area in front where you do not like the grass running up to the house. I would put a taller shrub on each side with the white stone. In the long planter I would remove some of the plants to make room for a Japanese Maple. As far as your front entrance: I believe I would demo out the whole area with the 3 smaller cement planters, and the steps. I would design a new walkway to the door. I also would attach a living wall section to the area with the smooth cement. Right now your front door is to small to have anything but a mat.