I don't mean to be dense, but don't all salvia need to be cut back or trimmed at some point?
I think S. forsskaolii could be a good one for you to try. The inflorescences are very sturdy and since it dies down in winter it shouldn't be that hard to keep in your zone.
You may also want to try 'Indogi Spires'. Cuttings root easily to be saved for spring planting; I don't know if it would overwinter in your area.
Cait

I am growing S. Guaranitica Black and Blue for the first time this year. So far it's 3 feet tall and is nicely upright, definitely more so than S. Indigo Spires was in my case. Diva