I really love the flexible content option in the pro version of the plugin, but there are a couple of items that I feel would help take this to another level, while allowing for the simple maintenance that it currently offers
1. Adding the ability to specify location rules on a layout by layout basis. This would allow theme developers to set very specific layouts on various page templates, and avoid duplication of the same layout grouping, cutting down on maintenance.
2. Providing layouts with an option to only allow the fields to be visible and edited by specific user levels. For example: I have an item on a site that we would like our editors to be able to position where they would like on the page, but the information that is contained in the fields should only be edited by site admins. What an editor would see on a page while editing it would be the layout, with a small descriptor specifying that the options are only visible to admins but they can freely drag and drop the item where they want.