To be clear, is the bar the freestanding area around the corner of the kitchen? If so I feel like a flat black may be a bit plain. But maybe a quartzite or granite that is black with some white veining (at least a moderate amount of veining, or even some dramatic patterns). I have seen some dramatic slabs that could look great as the backsplash per se of that cabinet. And on the counter. If the unit behind the kitchen is not the bar area then this comment may not apply. Disclosure, I am not a pro. Simply drawing from some inspiration pics i’ve seen.

I am really glad you want to make the bar stone different than the countertops. It is very popular. I don't know your comfort level with design or color. Rather than making the bar a subtle blend in, have you considered making it a bit of an eye catcher? I don't know your budget or if you are in area with actual stone slab "yards". If you have the ability, take a day and go wander around a stone slab yard or two. They may have a "remnant" that is big enough for your bar and a reduced price that can off-set fabrication costs. Check out Fantasy Brown Quartzite. If you still are thinking black, consider a  black and gold look like Volcano. You might be amazed at some of the natural stones with veins (movement) in browns and golds and taupe that would be a great complement to your countertops. Arizona tile has a large inventory you could look at on-line if you wanted to window shop for ideas. You could also see if you could find a "negative" of your countertops for the bar.

It's going to be such a lift, so refreshing when you get the new lighter counters tops!! Bet you can't wait. I think the flatback will make a statement and it will be beautiful! If you go tooo statement then it will forever be the thing you have to work around and you don't want that!!

Thank you for all the comments!! Yes the bar area is around the corner from the kitchen so part of the living room.

Do the cabinets in the bar match those in the Kitchen?

While you say "it's around the corner", it still appears to be open to and part of the Kitchen.

If the cabinets are the same, then go ahead and use a different counter -- I think it will work well. It's when people have both different cabinets and different counters that it can become a bit much. But, as long as one is the same, the other being different often works very well and breaks up the large expanse of counter color.

What you plan sounds good. BTW...I like your choices. I don't think I would go too crazy b/c you might get tired of something "eye catching". If you want something "eye catching", do it via accessories, not an infrastructure item that would be expensive (and wasteful) to replace in a few years.

Yes bar cabinets are the same as the kitchen ones. Thank you!!

Go to a local stone yard and pick a fabulous remnant! I have charcoal cabinets in the kitchen and did a built in stand alone hutch in an empty corner. My kitchen counters (which are FABULOUS) are Vicostone’s Misterio, white with very light and small grey/brown/gold veining. I chose a dark leathered granite with some caramel and cream running through it for the hutch. Everyone loves the difference and the remnant was a real cost savings.

Sounds lovely! Any chance you could load or send me a picture!? Thank you!