They don't look right because they are too close in color qualities.

Nantucket Gray is from the Yellow Hue Family and Ashen Tan is right nextdoor on the cusp of the Yellow-Red Hue Family and the Yellow Hue Family.

Two colors being close in terms of hue isn't always a bad thing. In fact, analogous color scheme means two colors next to each other on the color wheel - it's a basic color relationship.

The problem is a harmonious color relationship depends on more than one quality (or part) of color. So, if you're choosing to call it undertone that's fine but whatever you want to call it the bottom line is you can't base color relationships on just ONE part.

There are three qualities of color: hue, value and chroma. And they all matter when it comes to creating harmonious color combinations.

If two colors are close in hue, then there needs to be a healthy degree of difference in value and/or chroma. Value is about lightness and darkness. Chroma is about the strength of color.

And there in lies the issue with using Nantucket Gray and Ashen Tan together.

They are close in hue as I mentioned before.
They are close in LRV Nantucket is 39.4 and Ashen is 53.
They are close in chromaticity at right about the 1.5 mark.

First, you have to decide if you want to stay in the same hue family as Ashen Tan. The other option is to go with a color from the same hue family as Nantucket Gray.

Second, you have to decide if you want the kitchen color to be lighter or dark than Nantucket Gray.

Third, you have to decide if you would prefer the kitchen color to be less chromatic or more chromatic. In other words, less grayed or more grayed -- compared to Nantucket Gray.

And lastly, if you like the consistency, flow, and low points of contrast room to room, you could just paint the kitchen Nantucket Gray too. The contrast would primarily be between the Nantucket Gray walls and cabinets.

The Benjamin Moore site might be helpful. When you look up a color they will show you what goes with the colors, similar colors, and additional shades.

Here is a link that might be useful: Ashen Tan

Wow thank you for such an I'm formative and detailed response! Picking out paint colors that flow well throughout the house is even harder than I thought! I tried looking at the website for colors to go with Nantucket Gray, but it doesn't show any beige recommendations. Do you have any beiges or beige-grays in particular you would recommend?

I know this isn't a beige but more of a yellow, what do you think of Philadelphia Cream? This kind of leads to another question... if we were to paint the kitchen a yellow instead of beige, would it be too much color to also paint the dinning room Palladian Blue? It does have a doorway to the kitchen but it is not "open concept" like the kitchen and family where the colors really have to go together. We would paint the rest of the house, like the entry way and hallways, a neutral color but I am just wondering if the 3 colors would be too much color in the house?

I know this isn't a beige but more of a yellow.

The word beige is an odd word. Everyone defines what it is differently. Generally speaking (and when speaking to beige we can only speak generally because it is not a "real" color word) the colors most people label as 'beige' fall within the yellow-red to yellow hue families. Kind of like brown is just dark orange. Beige is just a low chroma light orange.

Nantucket Gray, Philadelphia Cream and Palladian Blue is a fabulous color scheme. No, I don't think it's too much color.

Thanks so much for all of your help!