Hi Andrew,
re accommodation in Valletta I can safely recommend the British Hotel in Valletta for its unique view over the Grand Harbour, mind you I can only speak for its views over the harbour because I have never spend any time in it, though friends who have worked there speak positively about it.
If you can book a room with a harbour view you could photograph ships right from your balcony, something just like our friend Jadran does from his famous balcony over the Adriatic.
You can also snap photos from the Upper Baracca gardens overlooking the saluting battery (and witness the firing of the midday gun, any new cruise liner visiting Malta for the first time also get a multi gun salute from the same battery). Then you could take the lift from the same gardens down to Valletta shorefront and cross over to the opposite side( by the small harbour ferry)of the harbour to the ancient walled 3 cities of Vittoriosa, Cospicua and Senglea (the best photo and shipspotters haunt).
From that same hotel ,and also any other accommodation in Valletta you could walk or take a electric taxi to Lower Baracca gardens which is practically over the harbour mouth.
There are other boutique hotels in Valletta and other small hotels.
Try to book early because if you are coming over in the Summer tourist season it would be very difficult to get accommodation if you are late in booking as the tourism is booming over here.
Looking forward to maybe meeting you at Senglea point.
Happy Holiday and photograph to your heart delight, will be viewing your pictures in the future on the shipspotting .com site.
Best regards from the island of Malta.
Emmanuel .L.