I would not go with a small tile backsplash just because the area under the window is shallow. That is what tile saws are for! End your tile at the edge of the upper cabinet on the sink side of the room. At the coffee bar, I would forgo a backsplash. It's not necessary, unless you are a real sloppy coffee pourer, and splash the walls, lol. Personally, I always match the grout to my tiles, I'm not a fan of contrasting grout, so picking out your tile will be step #1. Find a color that blends with both the countertops and your cabinets. Get samples and see how they look in your lighting. They are always different than they look in the store! Your kitchen will be beautiful when finished!

Hello, I don’t usually comment but you have such a lovely start I thought I’d hate to see it go sideways at the home stretch!

End the backsplash at the end of the countertop. It will look like it’s coming up short if you don‘t. As far as tile goes, there are not many choices so large they can’t be conformed to the space under the kitchen sill. I don’t know why someone would tell you to base your choice in a finishing look for the entire “frosting on the cake” off of one difficult area. Anything can be adapted to fill that space. Arabesque seems slightly busy in my opinion but you have done a great job in keeping a quiet, beautiful backdrop for decor. On the hand I’m so tired of subway tile in houses as a trend I am boycotting it for now;). Once you see a design look in every new construction home on the market, it’s pretty much run it’s course. That, though is a matter of opinion. I wish you well.

Great kitchen! We just painted our caninets the same color. We are considering Bedrosian Cloe tile. It is a white subway with beautiful variation.

are you doing some open shelves over the coffee bar area? I'd do tile and some warm wood shelves (not this color tile, I'm just showing you how it would look. but these are the larger format elongated picket style) The wood gives you some depth and interest.

where to end it is a personal choice. I happen to like it all the way out to the edge, but others like to stop at the upper cab. you have enough countertop so it won't look funny if you stop short. here's pics of both

doesn't matter if it's cabs or shelving,,,I'd take it all the way out. the backsplash is meant to protect the walls along the length of the countertop.

For tile design, I wouldn't do a small mosaic

you could do some pickets or the hive or even a scallop shape

or this herringbone. this is Tilebar Byzantine Bianco in a 4x12, above,,,and a darker ceramic style below

your kitchen is very neutral, so don't be afraid of doing a contrasting color.

another herringbone design w/3x12 gray tiles. cabinet color is Repose Gray.

Also, make sure you're bulbs are in the 4000K range. it won't cast the yellow tones that appear to be in your picture

Ill post some others in my next comment against Berwyn.

I would use a solid color tile which matches a light color in your counter. I would put a backsplash at the coffee station for continuity.

one other type of layout is the vertical stack layout. either in a straight vertical or an offset vertical. it's something diff from the overused 50/50 standard subway layout

you could do these with ceramic, brick, glass, etc. its more of a modern type of look

Here's Berwyn w/diff style backsplash tiles:

Soci-Cappuccino tiles

gray glass arabesque

gray subway 3x6, glass

Agora Piastrella Sage ceramic tiles

random linear bar glass mosiac in whites, blue/grays

looks like Lunada Bay Glass tiles

soft white 3x6 beveled tile

a warm gray tone 3x6, handmade look subway.

Those Soci-Cappucino tiles are beautiful!! That would look amazing in your kitchen!

I would end the tiles at the end of the top cabinets, but that is just me.

Because of the placement of the light switch at the coffee area, I would get a 4" backsplash that matches the countertop.