Under cabinet height, to the exact END of the counter top. Pick one, clock or pictures, not both , and move the light switches up and out of the way if possible

As Jan said. tile to the end of the countertop. make sure you get the bull nose tiles for those end pieces. bull nose means they are finished edges.

As for the outlet to the right of the sink. First off it needs to be a GFCI outlet (like the one on the left) and you could move those so they don't sit right where the top of the tile is going to be. What is that switch for? the disposal? a light? You have a covered outlet above and to the right. why don't you move that current outlet to that space and that way you can tile over the hole? make sense?

Thanks for the suggestions.