In our kitchen we considered the backsplash as an extension of the upper cabinets and ended it at the end of the uppers, using some black pencil tile as a border around the backsplash tile. We agonized over the detail, because we knew there would be a small section of wall showing in some places. I linked to our kitchen so you can see the compromises and decisions we made.

I see the trouble you're having though since the upper to the left of the sink does not end up flush with the lower cabinet and anything you do is likely to accentuate that difference in cabinet width. I think you're on the right track with going to all the way to the door, in the other two areas, stopping in-line with the uppers looks fine, and the stainless border would finish things off nicely.

I don't really know how to resolve the detail of the top of the tile overhanging near the door, you might want to try the stainless, or it might look better without.

If you stop level with the uppers, looks like there would be enough clearance for the lightswitch. Otherwise, maybe you can change to a double-wide box in place of the current triple, align it to the right, and use a double switch in one of the sides?

Here is a link that might be useful: Finally finished! forum thread