Where are you in zone 8 (general location)? South Carolina is different from Texas which is different from Arizona which is different from Oregon. It will help people give you a more helpful answer.

Something to think about- many crepe myrtles are actually trees. I have one that's over 15 ft high, still growing, and it died to the ground during an Easter freeze about 15 yrs, ago. Unless yours are dwarfs, they will probably outgrow their space. If they are full size you may want to relocate them to a different spot. They are beautiful trees.

I am in desert north of Vegas, so low water plants are best. That is a good point about the crepe myrtles. I may move that one to the end of the row where there is more room. I actually would love something tall in between the roses to cover the view of the neighbors' roof. But I don't want to crowd out the rose bushes either.

Ceanothus? they are gorgeous,and there is at least one lower-growing variety Ceanothus repens...

Crepe Myrtle attract Japanese Beetles, which will be a disaster for your roses!

Drought tolerant perennials that go well with roses are Russian sage, Salvia, culinary sage, dianthus, agastache, and achillea. Lavender may work in your area. It needs well-draining, sandy soil and doesn't like high humidity.

Does NV have Japanese beetles? If so, they'll find roses regardless of Crepe Myrtles.

I don't know anything about NV gardening but think bearded irises might do well. They mostly bloom when roses bloom and come in so many colors. If you go to an iris specialty nursery you will see an amazing variety of color combinations.

Verbena bonariensis is another drought tolerant plant that blooms with roses. Rose campion is drought tolerant. I think in general plants with silver leaves do well in drought, like artemisia and lamb's ears. I like the silver leaves for contrast. Rudbeckias can take some drought, and tall phlox. You could transform that space into a colorful tapestry!

A few very hardy evergreen shrubs I currently grow in z8 Texas, alkaline soil, some caliche:

Dwarf yaupon holly

Golden Euonymus

’Sunshine’ ligustrum

Abelia — ‘Kaleidoscope’, ‘Edward Goucher’, ‘Twist of Lime”.

Lots of great drought-tolerant perennial choices ... you can’t go wrong with Salvia greggiis or other salvias/sages. Rosemary would do well, too, as a shrub. Other tough ones:

Gauras, catmint, Oenothera ‘Lemon Drop’ (mine below in hell strip), Drift rose (also below), Mexican Heather, dwarf Nandina ‘Firepower’, feather grasses (make sure they aren’t invasive in your area), and the toughest of all — lantana.

Mealy sage with a ‘Texas Pink’ phlox (will bloom in a couple more weeks) and a mid-size crape myrtle that I limb up:

I love lavander, catmint and chives! That’s what I have right now anyways

My roses are not in bloom yet. i gravitate towards pink/peaches roses and love white, purple abs blue with it

Kate, I live in a hot desert area, too, and I've grown almost all the plants on frenchcottageaussies' list, and they are good in the dry heat. I particularly like lavender (likes well draining soil, but it doesn't have to be sandy; I grow many lavenders), and butterfly bush. I don't think your area has Japanese beetles to worry about--we don't have them, either. I'm sure your soil is plenty alkaline, so bear that in mind. Lynn in Texas, but formerly of Las Vegas, could probably give you lots of tips. Diane

Many good ideas, thank you all! I am especially drawn to the purple and blues. I picked out some lavender I love. I really like the salvias and Russian sage. Rosemary may be my evergreen shrub to throw in there. I'm a little nervous about making weird plant decisions as I try to fill in some plants! Any thoughts on how many plant varieties I should be adding in at this phase?? I don't want to get too hodge podge! 😬

Not knowing how big the area is we are talking about, I would say as a general rule get at least 4-5 of each variety (depending on size) that you plan to use and plant them together in groups. That way it won't look "hodge podge" ;)

That will be great, Kate. I packed in too many fillers here.