I am sure that you realise that the Radisson Narita is about 2-3 hours from the city centre? I am not sure where the other Radisson is.

What to do? The lights of Shinjuku, the Meiji Shrine, the Takuji fish market early in the morning, followed by the best sushi/sashimi breakfast you'll ever have!

Go for dinner, or at least drinks at the New York Grill at the Park Hyatt Tokyo - excellent food and the best view of the city by night that you can imagine from the 50-odd floor you're on.

Visit the Imperial palace grounds, go shopping in Ginza (and of course it is not cheap, but it is fun!)

So many things to do, so little time....