Wow talk about a DIY project. It takes a long time to do cabinets. Great job...I had a friend redo her old kitchen except she painstakingly painter her cabinets white with new drawer pulls. Kudos to you it looks wonderful.
Your kitchen looks great! Congrats! We redid our kitchen last year and I know how great it feels to finally have it finished up.
Regarding the non-matching area, is it wood or veneer? I'd go for 2 different finishes on those areas. For the upper area, I'd sand & stain that area to match the cabinets. If you're very careful and do light coats you should be able to get by without any streaking. In theory I like the chalkboard paint idea, but I really don't think it will work well for your area. That's a big area to be painted solid black. I think it will make things look smaller and more closed-in.
For the area below the bar, I'd definitely paint that the same color as your walls.
What color are the walls just off that area? Is it possible you could do both areas as an "accent" type color?