I’d go all the way to the door frame on the right and all the way to the opening on the left. I’m not an expert though.

Opening on the left - do you mean stop on the wall or around that ‘door’ frame corner?

Stop at cabinet and countertop n the right. Going to doorframe would look odd there. Extend to end of countertop/wall on left. Can you go all the way to the top and around on left wall? Need to see another picture.

I prefer the look of lining up the edge of backsplash with the upper cabinets, not going all the way to edge of wall. It’s a much more tidy, streamlined look. But your switches might need to be moved (and colour of plates changed depending on backsplash colour).

You don’t have to have a backsplash at all along that section… you have a lot of switches in that small sliver of a wall in an area that will most likely not have a lot of “splash” anyway. I would just paint the wall out and live with it as is. Can you add a picture of what your whole kitchen looks like?

I wouldn't add BS to that run of cabinetry, leave the 4" backplash as is. It's fortunate that your sink does not require a backsplash. However, I'm not sure what you might do concerning backsplash in the range/stovetop area of your kitchen, which we cannot see.

Nice backsplash ideas

https://home-design.bg/grub-za-kuhnq-vodoustoichiv-lepqsth-i-dr/

I agree with @theresa21 - a BS would just add more visual clutter than function under those cabinets. I'd do the 4" curb on that section and call it a day.

There is not a 4” curve there. That is wall (where the old counter was removed).

Line up the backsplash tile with the end of the cabinets.

I like the backsplash o go to the end of the counter that is where it belongs .

You can also think about not doing a backsplash tiling in that area you are showing, since you really do not have any washing or cooking elements there. So, you might want to consider a nice paint color and just keep it painted, you could consider a durable wallpaper, or even tinted glass to create a conversation piece.

I agree with Patricia. To me, the backsplash is the backsplash for the counter -- therefore, the backsplash should end where the counter ends.

I agree with Patricia and RTH. Please remove the 4 inch if you go this route. Otherwise leave the 4 inch as is.

You have a nice blue paint that creates visual interest, leave it at that.

There is NOT a 4 inch there. It’s an illusion from where the old 4 inch was. The countertop is flat

RTH - so then the tile should end on the right where the counter and cabinet end and then on the left it should go to the end and around d that little corner? If you zoom in there is no 4 inch anywhere.

Sorry for all the confusion. This is all referring to subway tile on the wall.

It looks like on the right side - the end of counter is a bit more to the right compared with the upper cabinet. I would end the backsplash so that the right edge is aligned with the counter edge, not the upper cabinet edge. You need to consider the light switch as well. I think it may look weird if part of the switch is on tile and part is on drywall. You may have to extend the backsplash so that all of the switch is on the backsplash.

Do you have the tiles already? You can lean them on the wall so you can visualize how the different options look. Or try pieces of paper cut the same size as your tiles - tape them on the wall and see how you feel.

If it's the switches that are creating a dilemma, then you can change them to combination switches. That replaces one switch with two switches, in a single gang box.

This would be my solution for the right. Move switch to the left and end BS at upper cabiinet. https://carlaaston.com/designed/where-do-you-end-a-kitchen-backsplash. 

I'm not sure about the left, I think I would end at the edge of the sink opening and not wrap around into the interior of the opening. I wonder what's going on with the other side of the opening. Can you mirror BS termination on both sides of the opening?

We need to see that entire wall of cabinets to make a recommendation. What is to the left of the sink? You want BOTH walls to have the same treatment. And, yes, you can have your electrician move the switch that is awkwardly placed on the right to be “inside” the tile backsplash. I had my electrician come back and relocated ALL my switches/outlets when I realized they were on different levels and would totally screw up my backsplash. He wasn’t happy, but I was happy. And isn’t that the point of a renovation?

Here are a couple more photos.

Your kitchen is going to be beautiful! Seeing all those switches and the 4” mini backsplash section makes me wonder if you wouldn’t be better off with just a 4” piece of your counter as splashback instead of trying to figure out moving switch plates and keeping the backsplash placement consistent.

That is an interesting thought and one that hasn’t been considered!