It looks like your garden doesn't really begin until summer. Why not plant spring bulbs. Tuck them around the late arriving perennials. All sizes, all colors or whatever suits your taste. Be aware that 4'oclocks may re-seed next year. They do in my garden. You also might want to consider backing the garden with an evergreen shrub for structure. Or even a dediduous one.
Happy gardening.

Thanks! Yes, spring is pretty dull. I really didn't get excited about gardening until after spring. I'm getting up earlier on weekends and before work now to work in my garden

When you pull out a clump of 4'ocs, dig in a round patch of daffodils at 8 in deep, then blue muscari at 4 inches. The muscari will send up shoots almost immediately to mark the spot. If you make at least three round patches of spring bloomers with a double layer of bulbs, you will lose some of the mish-mash look. I just bought some blue and violet
'icicle' pansies to intersperse in a long curved bed of muscari. I usually sprinkle easy to grow calif. poppy seeds among my bulbs when the foliage turns ugly.
I would stick with one color (like yello) in the daffs. and one kind and color with the muscari too. (usually an intense beautiful blue)
Chunks and mounds of one color look good. Broad, sweeping bands of one color look even better.
I like to see many different plants of one color, say all yello or all pink, planted in large swatches. Spark it up with a contrast of white or blue. OOOOH, so delicious!