I would pick a grout color that is darker than the tile. Would make the grout lines recede rather than pop and would make the backsplash look more integrated with the granite, since the granite is mostly darker than the tile.

Do two sample boards. I would like to see a full picture of your cabinets. I don't think the floor would be a deciding factor here.
This is a matter of taste. You can't go wrong with either. But again, one might make YOU unhappy. Do the sample boards and let them dry, Post them with a view of the cabinets and then a closeup with the granite.
My favorite is to have the grout blend in. That said, there are many on here who have gone darker and they look really good. This can be done to tie in the backsplash with the granite or they just want the backsplash to pop. Your color tile looks like it goes well with your granite.

pick the top color on the right sample card in your pic. It blends, and has a bit more gray without being gray...[or whichever one achieves this effect]... With the stainless hardware on cream cabs this will work with that.

Whatever you decide, be sure, as "ellendi" suggests, to make a sample board.
It's been my experience that grout dries significantly lighter than the color charts.

"It's been my experience that grout dries significantly lighter than the color charts."

This could be because tilers often use too much water during the process which can either leave them coated with effluorescence or wash the pigment out (this one is irreversible).

If they will do sample boards for you, great. You might try placing colored paper (painted with sample pots?) underneath the tiles to get a feel for the effect. You would at least could probably see whether you like lighter or darker. You can see what a dark one looks like now. The more contrast, the more pattern, so keep that in mind too.

Pretty combination!

Sample board. The sticks are pretty useless. You have to see it between your tiles in the width you plan to install leaned on your counter and see it with your cabs. See this in daylight and night. Despite whether the tile guy or loved ones say - it does not matter.. you will hardly notice it.. trust me.. you will. With your BS tiles, I would play with a darker grout or a gray grout to match it to the granite.

If you do sample boards, be sure to let it dry, at least overnight, maybe another day. The grout lightens as it dries. Also, make sure to use the same type (sanded/unsanded) as you plan to use in the installation. The color can vary quite a bit between the two types. We used the same color of both types on a backsplash and a floor, and the color was not really the same.

We installed the tile then decided on the grout. We liked the look of the lines between the tiles, so we went with slightly darker grout to show the pattern more. If you would rather have the pattern blend in, pick one closer to your tile color.

Don't worry, you'll get through it. :)

Thank you all so much for your input which has been extremely supportive, wise and helpful. Today I went to Home Depot to proceed with the sample boards. I am beginning with the blended (picked exactly the same one as herbflavor mentioned...color is fawn)and will move on to the darker, contrasting grout. I know gray is an option, but I am kind of afraid to go that route but may as well try in a sample board. Even after purchasing the materials, I am wondering if I should do the sample boards myself or ask the tile setter to do them professionally. I am anxious to see the results, so I will probably give a go myself. Thanks again, so much!