You can take a spectacular walk along the sea around the outside of the city walls. If you go to the mooring place where the ferry for Sliema leaves, there is the possibility to walk over the rocks towards the tip of the peninsula and then around it coming back up into the city just next to the Malta Experience. This walk takes about 30 minutes and is done by virtually no-one.
At night in St George's Square, there is a lovely water fountain, with coloured spouts of water which pop up and down - a fantastic play opportunity for children. They WILL get wet, so don't let them go near if they are wearing their best clothing. Great fun for kids.
Several of the Maltese English language institutes are in Valletta.