I think the most perfect solution would be the simple solution common in so many other todo apps and in Gmail, GDrive and other kinds of apps, too:

When you go through your Next actions (or delegated Waiting For action or whatever) to be able to star or unstar tasks. The ones that are starred should normally remain in their original position (not be removed from that list), so you can easily see which Next actions have been starred and which ones are not. Starred actions (from all lists) should then ALSO be visible on the Today list so that you have them all handy if you want to do something about them later in the day (and so that you do not forget).

This is one of the simplest and most necessary changes required in Doit. Nobody should have to go into some special "plan" mode just to do the obvious things you need to do throughout the day.