IMHO - I would do that - I would make my office door stands out and the warehouse door blends in with others. HIH-

Ok first, two grouts are incredibly easy :) My tile guy has done it all over the house for me...for instance, each row of this carpet has a different grout color: (this is pre grout by the way, but the grout is perfect in each row and matches exactly): So don't let that stop your decision. It's an easy process. They just apply blue tape where the grout isn't supposed to go, and then apply as usual. No biggie at all!!! Follow the manufacturer instructions! I did't know it was handmade. Mine is as well and there can be variation in both slope and size by very very little, but when you put up the tile, that variation becomes huge. 1/16th here and there isn't visable to the eye, until you try to make your poor tile guy do a 1/16th grout line. So go with the manufacturer recomendation. With larger grout lines, it's even more important to think of color of grout and again, I'd say use two. The reason being, look at my tile...if I'd used say a white or beige grout, (the grout is called Pear) the grout would scream at you, but the pear blends in pretty well. Big grey grout lines in the tan tiles isn't going to flow as well IMO.

I like your colors so far and the way the refrigerator blends. Deedles' suggestion is a great way to go to integrate what you have into one cohesive pretty look. This is what I would do, but it's not the only possibility. If you enjoy the look of separate blocks of colors playing against each other and want to continue that direction instead, you could use the curtains to introduce another block. You could either go relatively calm by choosing a color (or overall color in a patterned fabric) close to the ones chosen, like a gray-green or lavender blue. Or you could add more energy by contrasting with something like a yellow or orange. In both cases, since your existing colors are medium on the lightness-darkness scale and medium in brightness, neither crayon-bright or dull, the most foolproof way to achieve a look that really works would be to do the same with your curtains: medium/medium. That way contrast is kept to the actual pattern or hue chosen, while the other factors remain harmonious and allow it all to work together instead of fighting. Have fun.

Following up here, as we still haven't started construction on our project (although the cabinets did arrive!). Thanks to @cawaps advice about snagging on pants we looked for other options and we like these ones: https://www.gliderite.com/87227-5-screw-center-solid-square-cabinet-bar-pull/, in satin nickel. We might still go with nickel on bottom and black on top, but most likely we'll just to nickel. The one thing I still have left to figure out is the sizing. I think the 5" size is good for almost everything, but we have 2 30" wide pots and pans drawers, and I think it'll look silly to have a 5" pull on there, so I'm thinking we get a ~12" one for those two drawers. Does that make sense? Any advice on this?