The most ambitious extension on this list, and the one requiring the most advance planning: both ferry and short-flight routes exist between Malta and Sicily, and which suits better depends on schedules as much as preference.
Getting There
Compare flight times against ferry timetables before booking. A short flight is often the more forgiving option for legs that ran a marathon days earlier, while the ferry suits travellers who'd rather avoid an airport for a short hop.
Sicily's Layers of History
Sicily adds a different historical register entirely: Greek temples, Norman cathedrals and Baroque towns sit alongside each other in a way Malta's own compact history doesn't offer. Four nights is enough to cover one or two bases properly rather than rushing between many.
Where to Stay
Catania or Palermo both work as a first base, with good onward transport links to the island's other historic towns.
Getting Back
Return to Malta by the same ferry or flight route used outbound, checking schedules again before the return leg since frequency can be limited outside peak season.