The right guests are the people who can decide something based on what they see. Those are not always the most senior roles. They are the people with influence over the purchasing decision or the implementation. Determine those people first, and then develop the invitation list.
Send a personal invitation with a clear promise: not what you show, but what they take away. Avoid generic phrasing like 'come and see our new product'. Better write: 'Discover how [product] solves [specific problem] for teams like yours.' That specific promise attracts the right people and immediately filters out the others.