What goes with Siberian irises?

I have new groupings of Siberians irises that are dark blue with a gold signal. One will be next to a dry creek bed and get about half a day of sun and will need something to help them show up from a distance and have the same water needs. The other group will be in a bed with dogwoods and azaleas in front of the house next to the driveway and maybe don't really need anything else with them as they are pretty up close and personal already. They will get sun all day there. Any companion plants have to be perennials.

They like lots of water till they are firmly settled into their new homes.

I grow them in my borders amongst everything else and just throw an extra bucket of water at them from time to time.
Inanda

I grow some of mine with Lady's Mantle and Jacob's Ladder, Asclepias incarnata, and Turtlehead near a pond. and Astilbe.

I grow them in the back rows of my regular flowerbeds. They seem to bloom just as well in dry areas as wet areas. My mulch tends to maintain a certain amount of moisture. They are surrounded by Tall Bearded iris, Clematis on the fence, Phlox, Speedwell, daylilies, Lilies , coreopsis, snapdragons and anything else that has slipped into my beds.

Thank you so much everybody for your help. I guess I was more worried about them 'cuz they are new to me.