It's always risky to "almost" match...tends to look like you tried to match and failed. You are probably better off doing something different. Also, think about room function and delineation between private and public space. Tile may not be the best choice for bedroom flooring. It tends to be cold under bare feet unless the floors are heated, and the hardness of tile is often less suited to the calm of a bedroom than to the high traffic of a kitchen. If you do choose to do tile in bedrooms: If the bathrooms are a "private" space (serving the bedrooms), you might consider re-doing the bathroom flooring to match the new bedroom floors. If the bathrooms are public (serving the kitchen and dining rooms), coordinate with those spaces.

One of the bathrooms is en suite, and I would plan on redoing that tile. The house is in Florida, so cold floors are not really an issue. I don't want to just replace carpet; it's just dusty. I could do wood-look tile or something like that...

Agreed that carpet can be a pain to clean. Since temperature is not an issue, go for the tile if that is your preference; the big aesthetic takeaway here is that something obviously different in appearance (whether a different tile pattern or a different material) than the existing tile is safer than almost matching. If you are up for considering different materials, my material preference for bedrooms is hardwood - a touch softer than tile and easy to clean. Depending on your floor construction, engineered hardwood might be a better option (for example if you have a concrete slab rather than a wood floor framing system). You would have to shop around carefully to evaluate quality as some engineered hardwoods have a relatively fragile veneer subject to scratching. Whatever you choose, just be sure to discuss the specifics with a good local flooring contractor to make sure the installation is compatible with your floor construction.

Thank you for your thoughtful response! One other issue: we use one of the bedrooms as an office, and use rolling office chairs. If we go with tile, should we stay with the 20" tile size of our other rooms? And how do we manage the color merge at doorways? It's such a conundrum!

depending on your layout.... perhaps if all of the bedrooms are off a single hallway, redoing that hallway to match what you do in the bedrooms would give you a single transition point rather than 3 or 4.

This is the floorplan. All yellow shaded areas are 20" tile on diagonal. Bedrooms and closets are all carpeted. We use bedroom 3 as an office.

The best way to test the rolling chair issue is to bring the chair into the already tiled areas, roll around, and see how it feels. If it's bumpy and annoying you have a few options: 1. Pick a tile that is long and narrow in proportion and lay it in the direction you will likely be rolling to minimize the number of joints you will roll over. 2.pick a tile with relatively square corners and lay it with joints as tight and flush as you can to minimize the surface variation. 3. consider an "area rug" of stick down, low-nap carpet tiles at the desk (though you will have the same issues with cleaning as with full carpets and will be covering your nice new tile). At doorways where tile transitions, a common approach is to use a stone "threshold" to separate the different tiles. Ideally it would be single piece of stone at each doorway that plays well aesthetically with both tile types or directly matches one or the other. You can also just butt the two tile systems together, but that is a more modern aesthetic which is tricky to install well and may or may not go with the style of your interiors.

With tile, I'm not too worried about the chairs rolling on it. I just want to know if :1. I should go with a 20" tile on the diagonal, or if I should go with something completely different (rectangle, plank) and 2. should I just go with something that tonally goes with the existing tile.

1. Since the new tile will be in relatively small, unconnected spaces, 20" tiles may feel too large for the space. I would go with something smaller, maybe 12"-15". If you like the look of the squares on diagonal you have now, no reason to change the layout for the new tile, just the size. 2. The color of the new tile should coordinate with the existing but not try to match. As you shop around, get some samples of tile you like and set them next to the existing floor to make sure they don't clash.

Thank you so much for your input. It has been very helpful!