The hybrid delphinium  'Guardian Blue' has these amazing two-toned petals, shown in both photos above. It is absolutely arresting.

Delphinium 'Aurora Blue', at left, is a clear mid blue with a white bee. Below, a closeup of two cultivars - 'Magic Fountain Purple' with the dark bee and 'Aurora Blue' with the white bee.

The Belladonna hybrids are more airy than the elatum hybrids in the photos above. The photo below, at left, shows the light blue belladonna and the darker blue bellamosum. The photo at right shows the tissue-cultured delphinium cultivar 'Trick'. I haven't grown it because it costs more than $2 per plant - but isn't it gorgeous? (Photo of 'Trick' by Craig Yoshida at Gloeckner Seeds)