My back splash is "L" shaped. The vast majority of it is 12 3/4". It jumps up to 17" behind the range. I am using 4" ceramic that I am going to tilt on a diaganal and make a diamond pattern. The electrician in me screams to center the tile vertically, which will create an awkward pattern on the bottom, which I can see as well as the top which I have to squat to see. If I dropped the tiles down just a bit I can have a half then a whole tile on the bottom and whatever happens up top just happens. Is that the correct way to do it???
Also do I start tileing from the corner??? so I have half and whole cuts there and work out in both directions?
Your best bet is to draw it all out on paper first, as you don't want to leave gaps in the top or bottom-- it should all look symmetrical and like it was planned to fit the space. Are you using any decorative tile around the edges-- that might be a way to cover some of the smaller gaps.
Another thought, however, is to make the taller area by the stove a different pattern or coordinating tile to make it a focal point.
You don't have to buy expensive accents to make something like that look good. You can use a different size of the same tile - maybea different color - but I think just altering the direction of the tiles would be nice.
At this present moment in time I am making cabinets for the kitchen - just in case you wanted to know what I'm doing when I'm not around.