Do you have a favorite color? There are pinks, reds, blues, oranges, purples...which would all contrast nicely against a white house. What height would work in the space you have available...they vary from really short up to 40 inches or taller. There are so many to choose from...it helps to know what you like...fragrance, re-bloom, etc. Then maybe we could help narrow the field for you.
The other way to choose is for people to throw out names of some of their favorite hardy irises...ones that grow well, multiply, and are relatively problem free. Then you could look them up and see what you like.
If you want instant impact then you might want to consider buying several rhizomes instead of getting just one. Many of us only buy one so we can afford to buy a lot of different cultivars/varieties.
Anyway...these are a few things to think about.
Paul...'Bert' and Roberta are the same person!
Also, are you interested in historic plants? Iris go back a long way and (obviously 
) the forms, colors, and such have changed over the decades. For example, my house was built in 1940 and the Iris that were here when I bought the place are of the simpler, no-ruffled form of that time. Of course, I am bringing them future-forward thanks to our ATP folk, but still a good contrast to have.
That's All Folks.
