If you want extremely large blooms, here are the three I think of right away, although they are more expensive depending on the source -- but what garden impact!
AMETHYST PRISM - My favorite at about 9"
AZURE PRISM - Slightly smaller blooms and the scapes are a few inches shorter
MY CUP OVERFLOWS - A diploid, blooms around 8"
And here are two that I always think of as "dinner plates" when they bloom. The plants are shorter and the blooms really aren't all that huge, but they have great impact.
TEN GALLON HAT
PORT ORANGE
