Kmama:
You may take a look at S.guaranitica"Van Remsen"or some of it's hybrids S x"Purple Magesty,S x Jeans Purple Passion or
Betsy's Choice. S.coccinea (species only) your thought on
"Indigo Spires" is a good idea too.Salvia regla is one I
have in afternoon sun. Another thought would be S x Red Velvet
that is one of the taller greggii x microphylla hybrids
in my garden.
Have fun!
Art

Most of your Salvias will need a good cutting back to look their best. I've been growing Mystic Spires for 2 yrs now and it has never gotten over 3ft. Indigo Spires I think is well worth the extra effort to keep it in bounds if you're inclined. There are nice microphyllas that will bloom all summer and grow tall but I don't know specific cultivar names. S. Regla seems like a good fit for your space and light requirements but it only blooms in late summer/fall and then goes decidious.

S. elegans might fit your needs. Mine started blooming late last summer and is just finishing up now. Another of my favorites, although I'm sure many would disagree with this suggestion, is S. uliginosa. It can get crazy if you over water it. If you keep it on the dry side it tends not to get so crazy. Good Luck.

I have grown the salvia blue ensign for 4 years and each year they get bigger and fuller. They now easily reach 5ft. I grow mine on the east side of the house but I wouldnt think you would have problem on the west side.

salvia blue ensign in the back doing battle with tutti frutti
{{gwi:1239292}}

here is a flower closeup and hummingbirds love them should that interest you

Thanks everyone!