If you want to go to Malta, go in the spring/summer - we went for two weeks and we loved it. January will be miserable weather, not far different from UK but warmer....
Take the tourist buses, there is an open top bus which tours the island, well worth the trip then you can see the places where you want to stop and spend more time. There's one on Gozo as well, despite what Mark says it's worth a day trip - distances are so small - we bought local cheese to bring back. Maltese wine is lovely, but difficult to source in the UK other than through the Embassy.
We stayed in St Julian's/St George's Bay - 10 minutes from Valetta on the bus. The buses are excellent (especially now they have the new fleet) and it only costs a few euros to travel miles. Taxis are fixed rate, it was 20 euros from the airport to our hotel but we could have taken the bus to Valetta and out again.
We'll be back!