I find the Starter Roadmap view works best for my needs (drag and drop, names inside the bars, thick bars, easy to add existing or new initiatives/epics, etc) but there's too much going on in my roadmap to show all of the epics all of the time
Forced into creating master epics which are exact duplicates of the initiatives purely to enable the expand/collapse UX in the Starter Roadmap view
Apply this UX to initiatives! Expanding an initiative in the Starter Roadmap view should show all of the epics it contains.