While you'll see answers anywhere from 36" to 72", the norm is usually between 42" and 52", depending on where your vanity, mirror (or hutch), and electrical switches and outlets fall. You want to make sure that especially the electrical face plates fall either all on, or all off the FIELD tile (It can't have any raised tiles like chair rail or raised pencil liners falling underneath the plates, either).

Quick question...if my vessel sink is 21 5/8"L x 14 3/4"W x 7 1/16"H on a standard 24" x 22(?)" vanity, how high should my accent tile go in order to be seen?

Check the return policy at the tile store. they'll usually take back complete boxes, especially if you set it up at the time of sale. Better to get them all at once and know that they match. Though you really should open all boxes to check that there isn't color variation that needs to be mixed in. Don't count on tiles from two shipments matching!! Even such not so colored glass. You've been having a trend, late in the game, to cluttering up that wall. I have to believe it's for a reason. Is it because you really want a burst of color and pattern? Or is it because you've been living so long with the white blankness of it all? And the white, blankness of all that snow! I think with the tile all the way up, and the variations in the tile, the small format, and the grout, there's going to be a heck of a lot of texture and interest and sparkle on that wall. Rather than cluttering up the wall, I'd suggest laying in a supply of interesting window shades that you can change with the season. You can put bright brocades up in the winter, and cool bamboo in the summer. Blonde lace in the spring and earth tone herringbone in the Fall.

I completely agree with you, jerzeegirl. Isn't the whole point of a backsplash to protect the wall behind the countertops? I think it would look even siller to have that much counter hanging out there past the cabinets and backsplash. But I also do think it isn't very good design to have the top and bottom cabinets not line up when all you have is a stretch of wall on the other side or some other feature that acts as a natural stopping point. So I like the idea of adding shelves to the end of the top row of cabinets. Then there is no question about where to end the tile.