I visited 4 of the 6 Megalithic Temples in January 2015: Tarxien, Ta’ Ħaġrat, Skorba and Ġgantija.

Tarxien is located near the Ħal Saflieni Hypogeum (which was maddeningly fully-booked when I was in Malta), a 40 minute walk from Valletta. We passed through some quite untouristy areas and saw groups of African migrants (presumably 'boat people') looking for work. Malta is one of those countries shouldering more than its fair share, so I would imagine work is scarce for them.

Ta’ Ħaġrat and Skorba are near one another but far enough from Valletta that we needed a hire car. They are very low-key but you're likely to the only ones visiting, which is a plus!

Ġgantija is on Gozo and is the grandest of those I saw. Getting there required a roll-on roll-off ferry ride, but was worth it because the island is a treasure trove of photogenic churches and coastlines (we also visited the Azure Window).