Last night, I listened to some DK and to Christine Tobin. I recommended Tobin in an earlier post and must confirm that she is head and shoulders above DK.
Not only is her singing more authentic (I mean, she sounds like she's "lived the life"), but her interpretation and songwriting skills are incredible. She mixes in Mingus, Leonard Cohen (rearranged), Brazilian, some standards, and her own stuff.
My comparison:
DK = merlot; vodka martini
Tobin = whiskey
I particularly recommend Tobin's CD "Deep Song."