Helena Stube's is excellent, we eat there every time we're in radium...which leaves very little time for other resturants! But the Old Salzburg (German resturant) is good as well.
Helena Stube's is a small restaurant right in Radium and has excellent food. It's not particularly fancy inside, but every dish is excellent. It's often full on a weekend evening so reservations are recommended.
Nothing comes to mind in Radium, but just down the highway in Invermere there is a place called Peppy's. They do pizza and some other stuff and I have been there twice and loved it both times. Very good pizza and unique concept.
near invermere there is an old place called "the black forest" it's ok to good, but from the time i've spent in that area, it's the best that there is...