She has a great voice I agree with you. I never watched Duets, I was probably too busy with kid activities at the time. She did a great job there with Bon Jovi, but I agree with you it's just not the same since Richie left. He was a huge driver in the song writing, you never would have had You Give Love A Bad Name without him!
Great choices today, I enjoyed all three. The Darius Rucker duet was really good. I'll have to make a point to listen to some more of her music.