Some advice from the locals re hotel selection?

Both hotels are in the St. Julians area, which has no historical sites nor much shopping. Why did you choose there? I would advise somewhere on the Sliema Strand, which has a nice view towards the bastions of Valletta, shopping and only a ferry ride away from Valletta. Perhaps the Fortina resort?
You might also consider the phoenicia or Excelsior hotels. Both in walking distance of Valletta.
Swimming in the sea is possible from most coastal places. And certainly done a lot. You could also go to one of the many lido's along the coast.

Hi ECS

We have stayed in both the Radisson Blu and the Juliani.  In fact we stayed at the Radisson on our very first visit to Malta 6 years ago.  It was a nice hotel but the location isn't the best unless you have a car as it is the other side of St Julian's. We enjoyed our stay and it was generally  quiet despite being in the vicinity of the main clubbing area Paceville.  The Juliani is a a lovely boutique hotel, though with small rooms,  and it can be noisy as it is very close to the main road and  dining areas of St Julian's.

Seat OA has made some good suggestions for hotels. Friends of ours have stayed at the Phoenicia a few times and enjoyed it. It is very handy for the main bus routes to get round the island if you don't have a car.

Before we bought our apartment, we also used to stay often at the Palace Hotel in Sliema.  It's not on the seafront but is set back a bit from the Strand and therefore quieter. If you ask for a room on a high floor, many of the rooms have views over Sliema and the sea.  It has a lovely rooftop pool and the location is handy for many restaurants and good bus routes.

Hope you enjoy your stay. We did five years ago and ended up living here.

Charley

thanks to you both for the local advice- I did some further research based on your comments and ended up booking a private apartment through airbnb. It's on the waterfront in Sliema (fort Cambridge) and is very close to the ferry to Valletta. It's got a pool and a balcony overlooking the sea so I am hoping it's all the elements we need for a memorable summer experience on the island!