I'll second Jazz, it's more Mid-Town than downtown....definitely worth the trip.
And Peach Tree is unbelievable, it's in the 18th & Vine district.....close to the Negro Baseball Hall of Fame and Jazz Museum. And while you're in the area, you may want to try the World Famous Author Bryant's BBQ (off 18 and Brooklyn), they have the best BBQ in town IMO.
Another one of my personal favorites is Kona Grill, it's on the plaza.....nice area to walk around and shop too. They serve a variety of foods that include sushi and I'm not sure what you would consider the other options there really..but, I LOVE their Macadamia Nut Chicken.......makes me hungry just thinking about it!
I'll let you know if I think of anything else.