Whitecap:
Where in Zone 8 are you? your plant selections sound like you live in central Texas.
Here are a few that have worked for me.
Salvia guarnitica,blepharophylla "Sweet Names" if your looking for a reliable perennial.Do be aware they will
spread by undergound runners (like plumbago). They will
also need some water during summer.

Salvia coccinea,subrotunda,miniata as a reseeding annuals some water in summer.

Salvia regla, microphylla "Cherry Cheif",muelleri "Viva"
Salvia x Neovo leon which you may see marketed as "Navajo
purple" both these plants have the same growth habit and I
believe are the same plant. These are woody Salvias (for drier beds ) so you don't kill the melampodium leucanthamum aka Blackfoot Daisy.
All of the above Salvias have a longer bloom time than
S.roemeriana.
Art

Actually, S. roemeriana resumes full blooming when it cools back down. If you are in Texas, it should self-sow. Try adding humus from Juniperus species and limestone to the soil, since this sage does well in cedar breaks, where it grows in pockets in the limestone where needle duff accumulates. When I lived in Massachusetts, I mixed in hemlock duff and limestone in the soil where I planted it, and it did well.

Thanks. I'm in North San Antonio. I relocated the cedar sage to a more shady spot, and it will have to do or die there. For the bed, I'm looking for something with an extended blooming period. I tried black and blue sage, but had to remove it. It grew well, and was a great favorite with hummingbirds, but the blooms just didn't show up well from a distance. Shoots also started popping up 4 ft. away after just a few months. The bed contains little Texas clay (I probably put way too much organic material in there) and is watered with a soaker hose. I'll check out the recs.

Regla cold hardy only to 20 or so?

I've been looking at some pics of "autumn sage" shaded by a stand of cedar on the site of an Austin blogger (now inactive, apparently.) It's just what I would like, but it's not possible to tell how much sun it's getting.

Whitecap:
My S.regla has taken temps below 20 most of the forms
that are grown in our area are the Jame form which Lynn Lowery collected years ago. I have grown S.regla "Jame" in the hillcountry during the freeze of 89 which was in the teens for a week. It had some tip die back but returned. I would also use the same limestone caliche soils for regal and romeriana.
You can also try the S. guarnitica "Van Remsen form" it stays in one location . My Salvia microphylla "Cherry Cheif" has been in a shaded location for several years gets a few hours of late afternoon sun. Has maintained a nice compact habit and survived our temps without a problem.
S. greggii can get leggy looking in to much shade. I have seen S x "Indigo Spires" in a shaded location
but it too gets leggy without 6+ hours of direct sun as well.
Art

Sounds like the Chief is more the size I'm looking for. Thanks.

My regla has come back from a 11 degree dip last year and it has green twigs after this extended cold snap, this year. I am not saying anything because lots of my agave's are continuing to look worse. And my vegetables are continuing their sinking, even the ones that had a lot of life to them.

The Cherry Chief, set out just after my last post, has been a great success. It's now about knee high. The ratio of blooms to foliage is rather low, but the blooms are so bright they make quite a show. The cedar sage seems happy in its new, shadier location, and is blooming nicely. Be interesting to see if it again stops blooming when high temps arrive.

Several years ago, I stuck a cutting of S. regla in the unamended clay soil at the back of our house that faces northeast. This site gets bright shade in winter, and morning sun (until about 1PM) in summer. It has thrived there and still going strong. I tried this as an experiment -- nothing ventured, nothing gained.