Thanks for writing. One of my favorite companions for roses is perennial geranium --- there is a wide variety of colors and heights you can choose from. One exceptional variety is called 'Rozanne' --- and it blooms constantly from early summer to fall.
One note: If your roses get mostly shade, they'll probably start to decline over time. Iceberg roses do best in full sun. So you might keep an eye out for that.
---Justin, Senior Garden Editor, BHG.com