Go with a light tone like cbricharcds suggested to avoid a checkered pattern competing with the rest of the kitchen. Beautiful kitchen!

• Mine looks almost the same, totally go with backsplash color, you'll be happy you did!
  

If you want a spot on match use Custom Grout color #172 Urban Putty.

The color you are using is used a lot here in Texas. The color referenced above is the best to blend with the variation. Should be able to find at Home Depot, as they do carry Custom Grouts. -If by chance it falls as a special order, find a mom and pop shop that carry the grout. Home Depot doesn't usually carry all the colors for some odd reason.

Go with a SLIGHTLY off shade grout, so that it'll show off the brick pattern without overpowering the whole backsplash. A good example would be using something like Laticrete's Silver Shadow with a white subway tile. With this, I'd have to go to a grout chart to make specific recommendations, but I hope you get the idea.