
Alrighty then... if I'm prepared, might as well just do it then, eh?
It added about $130 to the budget to add an additional 25 square feet above the stove, but after thinking long and hard about it, I think it really would just look like a half-arsed job if we didn't take it all the way to the ceiling.

Thankfully, we hung the cabinets straight and at right angles, so I didn't have to worry about us not having 90* angles for the square tiles. (But I measured with a square, just in case before I got started.)
Once I drew my base line, I could start applying mastic to the wall, starting from where I left off on the right, keeping the spacing and all that jazz.

And my thought was this: Let's say in 2 years, I chuck a travel coffee mug at DH because he continually sneaks spoons and forks into non-silverware drawers in the kitchen. He ducks, the mug dents the hood, and there I am needing a new vent hood and a marriage counselor.
If I keep the DH, but replace the vent hood...well, if I don't tile now as much as I can, there's a likelihood that a new vent hood won't have the same shape/size, etc. and tiles will need to be added, as will grout, and the grout will have to be matched, blah blah blah.
So yeah, take the vent hood down and tile under the whole darn thing.

In the end, it was the rational decision.
But, hey... note the small electrical plug up there on the wall? That's going to stick out like a sore thumb as soon as you walk in the door. Yes, I'm planning on spray painting the hammered copper spray on the plate, but what about the plug? It was stark white.
We wanted the plug up there in case at some time down the road we wanted to change our lighting options and maybe need to plug in a transformer, but for the life of me, we've never used the darn thing. My concern with spraying the plugs at the counter level was that as we used the plugs, it was likely the paint would scratch off from use, but in this case, that's hardly likely.
So here's what I did....

Like a moron, I came up with the idea AFTER I had tiled around the plug, so I couldn't just willy-nilly spray all over the place. You see, if you have 2 brain cells to rub together, you think of this BEFORE you tile. Yeah.

Oh yeah, btw, as I tiled up the wall, I kept a 3' level nearby. Every few squares of tile I put up, I would check to make sure my lines were still going up level and plumb. You'd be surprised how easy it is to slip and move your tiles into a 1/2" downslope over a 6' span.

A few hours later, I was done and we put the vent, stove and cabinet back into place and made dinner.
The photo does not do this tile justice.
It looks so much better than I expected.
Of course, there were still minor adjustments to make. For example, in one line of tiles just above the stove, a whole column of tiles were a little offset. I just cut straight through the mesh and the mastic, pulled the whole column out and readjusted it.
There were also several squares that were tilted a few degrees of of acceptable, and a razor blade and a dollop of mastic set those right as well. Just don't be afraid to cut into the mesh and redesign as necessary.
Like w

Oh, and we've made some changes regarding the grout.
We are NOT going to use the mixed grout we tested previously. We have decided that although the gaps between the tiles are large enough (1/8" apart) to use sanded grout, we just didn't like the texture in the end. The gritty look of sanded grout didn't blend well with the shiny coppery tiles. We're going to go with a lighter green non-sanded epoxy grout... one that won't need to be re-sealed every year like the sanded grout.
Here are the problems:
1. We have 38 ft^2 of tile to grout.
2. Epoxy unsanded grout does not come in the same colors as sanded grout.
3. Sanded grout costs $18/bag would cover our entire area
4. Epoxy unsanded grout costs $90/bucket and would cover about 18 ft^2
5. We found the perfect color.. #13 lichen, but it's discontinued.
6. Did I mention that the unsanded epoxy grout would cost as much as the tile itself did?
And what if we had a plumbing or electrical problem and we needed to punch a hole in the wall... you can't regrout with a discontinued grout colour... where would you get it?
So the search continues for the perfect grout.
This could take a while.