The University of Iowa aikido club -- Iowa City Aikikai -- sponsors quarterly seminars where very high-ranking instructors from across the country visit for a weekend. Seminars are a wonderful way for aikidoists (new and seasoned) to learn techniques in new ways and to train with people from around the state of Iowa and neighboring states.
More details on the next seminar: http://www.uiowa.edu/~aikido/updates.html