I have bought last year Cherry Orkney. It is short with dark leaves and pink flowers. Seems to be a sterile hybrid, so it has been in bloom starting late May, does not show any signs of stopping either.
Karmina will give you couple of weeks of good bloom, but it is nice groundcover.

Are you happy with the Cherry Orkney? Looks like it blooms late May through frost. Flowers may be limited during humid hot weather.

Do the flowers stand out on the foilage? Some google pictures make the foilage look ratty.

I plan to put this plant in as a perrenial border in the front of the my house...placed in front of Coreposis Zagreb. So far the Zagreb has been vigorous and prolific with its blooms. After 1 year its 24" x 24".

Ratty Image:
http://www.mobot.org/gardeninghelp/images/low/C887-0717080gk.jpg

Looking good image:
http://www.warwick-gardens.com/images/plants/Geranium%20%27Orkney%20Cherry%27.jpg

very happy
so far it has been plant it and forget it plant no extra anything needed, flowers are prominent but at the level of the leaves so whole plant looks nice and tight compact

You don't have to deadhead the Cherry Orkney after blooming?