Hi Nic,
Being in SoCal, water use is a premium concern. Rather than running plant material in channels down walk, have you considered expanding beds in an undulating pattern to reduce the lawn? Rock mulch of different sizes, coupled with drought tolerant natives would be lovely. From succulents to agaves, native lilacs to cacti, there are a lot of interesting plants to choose from. Happy designing!

A wide pathway makes a statement. Rather that remove the pea gravel, I would take out a swath of grass on either side of the path and put in some low-water use plants. There are a lot to choose from on Bewaterwise.com.

In trying to add a decorative edge to the walk, using plants is going to be more work in the long wrong. I'd consider if a flush sailor course of brick would give it the extra spark you're looking for. Even though you aren't ready to throw in the towel yet, I think extending the lawn into the strip would be the best second choice. A planting strip probably needs to be 2-3 times wider than what the gravel strip is, and is going to be more bother than it's worth.

In SoCal, the lawn is more bother than it's worth!! I would also suggest creating a sufficiently wide planting bed alongside the gravel edging and plant with drought tolerant natives. The less lawn you have, the better!

1. The walkway is good but the wave makes no sense, the 'pebbles were a mistake, you could put something in the belly of the curve that would make sense of it.

I wouldn't put in the blue fescue posted. It's can get ugly certain times of the year. With the house in light yellow, a nice contrasting pop of color like purple would look nice. But those beds need to be twice the width of the gravel, unless you just put in annuals petunias in summer and pansies in winter. I think you want something more permanent. I would definitely remove the gravel as it gets into soil and then you can't dig. You might want the soil a bit lower than the pathway so soil doesn't spill over when it rains. I agree with lgteacher on bewaterwise.com has lots of ideas. Too bad iceberg roses aren't purple.