Does the existing hardwood go nicely with the cabinet color?
Is the dining room through the large doorway at the top of the plan? What are the other rooms and what flooring do they have?

Agree. Best choice is to refinish all the hardwood to a color you like. A flooring contractor can lay new hardwood in the kitchen and match it all. But I have no idea about in floor heating with a wood floor. I can't imagine it would work.

2nd best option - tile in kitchen and hardwood everywhere else.

Thank you. Yes, the dining room is the doorway at the top of the plan. Lower left is mudroom (no door, unsure of flooring in there, as of yet. will likely make it the same as the kitchen, but possibly something tough.) mid left is pantry (will continue kitchen flooring in there). The doorway in the upper left corner of the room leads to the den (a room which will also require new flooring). I'm leaning toward tile in the kitchen. We have five children, so I hope that it will hold up. I think I will look for an engineered hardwood that is similar to the hardwood on the remainder of the first floor for the den. There will be radiant heat in there as well, but it does not directly abutt any of the hardwood, so I think I can pull it off. I appreciate your input.

Looks like a really nice layout!

Thanks! We hope so!

I always try to get my clients to install radiant floor under tile flooring. If you are going to the expense of installing radiant heating, the heat is going to transfer best when its installed in the mortar of the tile.

That's helpful to know. Thank you. Probably going with slate, which is funny because it was central to my original vision for the kitchen.

Continue with wood floors in the kitchen.You can do a wider plank there or a diagonal installation just to create a design but be consistent with the color ,this will float with the rest of the home.
Just make sure you use a good finish like Bona high traffic water base at least 3 coats and that will last you a long time.

The wood will transfer the heat but it will be a bit slower than the tile. That means it doesn't "cool down" as quickly either. If this is "room heating" then a stone/tile surface works best. If this is "extra heating" to prevent your feet/legs from getting cold then engineered hardwood will do very well. Cork floor does the same without the need for the radiant heat at all...but I digress.

Electric heat mats/in-floor radiant heat is tricky with wood floors because so many manufacturers do NOT like electic coils against wood. Electric in-floor radiant heat has a long history of over heating/shorting out that is a risk up against wood. Hydronic heat tubes are the only ones we allow with our cork floors...reduced fire risk...reduced risk of over heating. The type of radiant heat will tell you what you are allowed to install over top. Don't listen to the people who sell the radiant heat system. Listen to the flooring manufacturers. They are the ones that warranty the floor, they are the ones who say "yeah or nay" to heating under their products.

When using wood floors over radiant heat /
White oak r/q or q/s are the only suitable .
installed thousands of sq/ft solid and engineered unfinshed
If you go for prefinished there are plenty of Armstrong ,shaw , products that have a warranty and are appropriate to install as long you use the right addesive
Sika and bostich make plenty of those and some of the a sound membrane reduction

It will be hydronic heat tubes, but thank you about fire consideration. It's important. I have always liked the idea of cork. My concerns with it are durability (water, high traffic), and aesthetic, I've not seen many examples that don't appear "dated". That said, I am still a fan of cork, and would be interested to learn more. I had wondered if it would be a viable option with radiant.