We did a whirlwind tour of Italy and then did a relaxing side trip to Malta. Direct cheap flights available on Ryan Air from several cities in Italy. We spent 6 full days and did not cover everything we wanted to see.
Transportation: I recommend renting a car to explore (also super cheap only $68 for the week!). It took us a couple days to be comfortable because you drive on the left and to get the lay of the land. Main road is double lane highway like but most are picturesque narrow winding roads. There is also a very cheap bus service that would work if you wanted to go from town to town but does require some schedule planning.
We traveled the first part of Dec and the weather was mixed high 60's to low 70's. Mostly sunny, overcast a couple days, only one rainy day, The sky and ocean rival each other with brilliant shades of blue. Just lovely.
History: Temples date back to 3600 BC. That's a 1000 years older than the pyramids! The history of the Knights of Malta is very interesting and the whole area is filled with different sights. The island originally connected by land bridge to Africa remains of dwarf elephants and hippo's have been found. The disciple Paul was shipwrecked on the island and many sites are dedicated to his visit. The National War Museum gives a wonderful tour of Malta history. From the Great Siege when the Turks captured the island to the siege of the Axis powers of Germany & Italy during WWII suffering 3000 bomb raids in two years.
Cities: Valletta is beautiful sitting on the waters edge with so much to see and do. St John's Co-Cathedral and museum is jam packed with paintings (Carvaggio), reliefs, sculptures, tapestries , marble and gilded walls. There is also the Grand Master Palace, Ft St Elmo, and other Knights of Malta sites. Just walking the streets is a visual treat with the architecture, Maltese balcony's, squares, and my favorite pasty shops:)
If you visit in a higher season be aware Valletta is a cruise ship stop. If possible avoid this area mid-days when they are docked.
Mdina/Rabat became our home away from home. This small, golden stone, Arabic walled city is charming. Originally fortified from as long ago as 1000 BC by the Phoenicians, then came the Romans, then the Arabs in 9th century. The Maltese aristocracy lived here during medieval times. Rabat is the town that surrounds Mdina. It is full a wonderful restaurants, shops and sites. Be sure to to stop at the Crystal Palace pastizzerija, a small hole shop that sell pastizzi (a small flaky Arabic pastry, served warm fresh from the oven, filled with either mushy peas or ricotta cheese & parsley) for only .30 euros each!
The Island of Gozo is a must side trip. Natural beauty of the Azure Window area offers a great hike. Victoria has the walled city of II-Kastell with awesome views of the island. There is a great roof top restaurant Ta Rikardu within walls.
Game of Thrones fans: The series has used Malta extensively. Most of which we did not even realize until returning home and noticing it while watching an episode. I had to google it and found that many of the sights we had visited just happen to be locations of the show.
The BEACH: We stayed on Golden Sands Beach. Bright shades of the most beautiful blues you will ever see. Bay after bay of sandy beaches. Great hiking along ridge from beach to beach.
Crowds/People: While there in the Dec we experience ZERO crowds but in season it sounds like it is incredibly busy. Malta is a haven for the British to escape their deary weather and because it was part of the British Empire at one time the official language is Maltese/English combo so communication is a breeze. The few tourist we came across were from the UK or Italy.
The Maltese people were wonderful. Very kind and genuine. Easy to talk to and just as interested in us as we were with them.
I can not say enough good about our experience!
I agree with all your comments, except the one about renting a car (this applies to early September, the time I went - very crowded). The only place I regret not having a rental was Gozo because it's so rural and the sites are all spread out. If I had a car while staying in Valetta, it would have been a waste since there was nowhere to park it and everything is very walkable (and I would argue you need at least 3 full days just in Valetta and around to see all the sites it has to offer). Valetta, Sliema, the Three Cities and surrounding towns are super dense and overdeveloped....I can handle most traffic jams but there are hardly even traffic lights, so you're driving in traffic circles and odd, narrow street configurations on the left with a manual transmission. Seeing this from the bus, I was so glad I didn't have that to deal with. Outside of Valetta/Sliema/Three Cities, it was much more doable but the bus system was great and inexpensive. It was the only thing that was well air-conditioned in September, when it was incredibly hot, sunny, and humid. If I go again (and I hope I do, but never again in summer/early fall), I'm renting a car in Gozo to poke around, but not anywhere else since the bus system does a good job connecting most locations (small villages obviously don't get as frequent service). For anyone who plans on using the bus, Valetta was the perfect location to stay because all the buses left from there.
Glad you ended up going after all, and had a great time!