Can the red include fuchsias or magentas (with a blue tint) or must they have a yellow tint (scarlet)?

Are perennials what you are looking for, or can you use annuals?

Van Remsen is a gigantic guarantica with bluish purple flowers. You should be able to get it at A World of Salvias. Mine which were grown in rich soil easily reached 7 feet. It won't be hardy for you but the cuttings winter over indoors pretty well. The only down side to this guarantica is that it doesn't start flowering (at least for me) until August.

Splendens Yvonnes is a big one but I'm not sure where you'd find it. Subrotunda is a tall orange flowered species that can top out at about 6 feet. The flowers are small but there are lots of them - a hummingbird favorite if that is your issue. It also reseeds very well.

Salvia miniata can get quite big in one year (4 feet in Massachusetts in part shade) and blooms as soon as late spring

You could try Salvia concolor, which can reach 10 ft.

Also S. gilliesii and S. haenkei.

Thanks all......great info. I'll start doing my research!

Salvia 'Blue Chiquita' (Blue Chiquita Sage)
SunZone: 8-9, at least 44" tall Origin: Mexico:

http://www.plantdelights.com/Catalog/Current/Detail/04253.html

Salvia darcyi is bright red and 48 inches tall:

http://www.plantdelights.com/Catalog/Current/Detail/00814.html

Salvia greggi Dark Dancer is 48 inches tall and a gorgeous dark red:

http://www.plantdelights.com/Catalog/Current/Detail/02636.html

Salvia guaranitica 'Black and Blue' is a favorite of mine. The hummingbirds love it too. It's 36 inches tall:

http://www.plantdelights.com/Catalog/Current/Detail/02016.html

And for really tall, at 84 inches tall, you might like Salvia 'Phyllis Fancy:'

http://www.plantdelights.com/Catalog/Current/Detail/06157.html

Here is a link that might be useful: Salvias

Here is a nice 6 'footer for you== It is Canariensis from the Canary Islands ,lite purple with large follage, very pretty salvia

don