I'm not aware of any serious attempts to find royal brides for any of the Vladimirovichi. This seems a bit surprising, given that that they were all rich and highly eligible, and their mother was ambitious for them. The point is made in The Grand Dukes that no serious attempts were made to find a royal bride for Mikhail Alexandrovich either, apart from an attempt to link him up with Patricia of Connaught.
Yes, Kirill did marry Victoria Melita and Mikail fell in love with Beatrice of Coburg, but neither was 'suitable'.
Ann