Unfortunately, in the new post-hamburger menu Android, the options that used to be available in the hamburger menu are now even harder to find. When they're still available in the main screen, they're also less useful--you have no idea what they do until you use them (I know I can long press, but family can't).
The best app UI I've seen, FBReader, has a menu, a drawer, and an action bar, and you can move elements between all three of them through settings, and for normal reading use the UI is hidden altogether. If you want to do anything advanced, it gets more difficult though--it has nested menus, though they're well organized IMO. Another UI that I like is Perfect Viewer's tap zones--it has settings for 3, 5, 11 tap zones on screen, and you can set what happens separately for long-press, single and double tap in each zone, plus swipe the top for brightness and bottom for progress control (like dragging a scrollbar, but for ebooks); probably overkill for most people though.
The best app UI I've seen, FBReader, has a menu, a drawer, and an action bar, and you can move elements between all three of them through settings, and for normal reading use the UI is hidden altogether. If you want to do anything advanced, it gets more difficult though--it has nested menus, though they're well organized IMO. Another UI that I like is Perfect Viewer's tap zones--it has settings for 3, 5, 11 tap zones on screen, and you can set what happens separately for long-press, single and double tap in each zone, plus swipe the top for brightness and bottom for progress control (like dragging a scrollbar, but for ebooks); probably overkill for most people though.