Malta is probably my favorite holiday location.
Never stayed at a Malta Radisson but going to stay at both as soon as I can spend a few good weeks there.
I would say St Julian's has by far the best overall location for a first Malta trip.
The problem is St Julian's/Paceville is pretty much the party neighborhood, if going from May-September, might be noisy and fairly uninteresting if off-season with lots and lots of empty places to choose from, but Malta is pretty empty anyway off-season, so...
But Malta isn't that big so from St Julian's you can get pretty much anywhere in no more than an hour. Maltese bus system is excellent. Just avoid getting a bus on rush hours, they will be crowded (I don't mind though, I did with a large suitcase once while switching hotels).
The Golden Sands property is almost on the Northern tip of the Island of Malta so it can be a problem reaching most places from there. On the other hand, you will be closer to Gozo (one of the three islands that form Malta, the country Malta proper and Comino being the other ones).
My tip regarding Malta is try to get as much information as possible before getting there. There are lots and lots and lots of things to do.