In a 40s house I would use square tiles (as are some of your samples) If you did not want to commit to an actual color but are interested in some pattern (as indicated by the talavera thought), how bout mixing in some delft? Its a vintage look but subtle.

40's does say 4" square or subway - I think a colour would be complimentary to the kitchen and a number of old 40 houses with original tiling that I remember seeing often had quite interesting colour tiles - but almost always 4" sq tiles.
My parents did a 4" tile but hand made/glazed that provided nice variation in colour and texture while staying with a traditional/period look.
Caspian

Pal and Caspian -- I agree with you about the 4x4's. I taped up 3x6 next to 4x4 to see if there was much style difference in reality and they looked equally good to me, so I would go with 4x4 in homage to the house. I don't think this kitchen ever had a tile backsplash (probably was laminate) but the original bathroom had white 4x4's with black edging.

Funny you should mention delft, Pal. DH (who usually only likes white and tan) said he liked the blue tape dots, and he wasn't joking. I'll see if I can find a source. Caspian, I've seen pictures of kitchens with the handmade tiles and they do indeed look very nice.

I like the square tiles. Maybe flip them on their side so they look like diamonds instead of squares? I saw that in canadian house and home. It looked lovely.

I do love the mexican tiles! Those cement tiles are oh so gorgeous. I don't know if there is a tile or a tile shape that echos the 40's. If you're dying for those mexican tiles, maybe start there.

OOOH! Came across this. California tiles were made in the 40's. It is american art tile. I put in a link for a book. Looks to me that those bright and beautiful tiles were put into homes in the 40's. So, it wouldn't be out of sorts in your home!

Below is a quick google search.

https://www.google.com/search?q=california+tiles&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a

Here is a link that might be useful: Amazon book

Ooh, what gorgeous counters! I just want to run my hand along them, they look so smooth, warm, and lovely!

I really like those 4" tiles by your prep sink. I especially like the three on the right with your wood and cabinets. If pressed, I'd probably choose the one second from the right--the slightly lighter one. But if you find gray depressing but like strong colors, maybe the green one or another color?

Great kitchen and love the counter. Nothing to add advise wise, but I just want to say that all of us thought the same thing when we were in the reno phase. My DD1 walked in and said, "This looks like an operating room." Things change once you move in all your things and add rugs, wall art, accessories etc.
White tiles with the white kitchen are still very popular here because it is an easy look to live with.
If you decide to go plain, check out the beveled or oushion tiles.
As usual, I like Pal's idea. But, you have to really want blue in your kitchen.
The backsplash is the easiest thing to change in the future. Of course it is best to make a choice that you will keep for the duration of the kitchen, but it is not the end of the world if you want to change it out down the road.

I would add some color to the room with 4x4 travertine tumbled stone, or small slate.

Seems to me you need to add some color somewhere. Only thing is if you add it in the backsplash, it's a permanent thing, whereas if you keep the backsplash neutral, then you can add color in the accessories and fabrics.

I doubt it's a 40s thing, but I'm into dots and cutting up a mosaic that combines the color of the cabinet, the field tile and the beautiful counters would be a way to add interest without setting a specific color scheme.

Question, though, how high will you go with the tile? will you do the entire backsplash, or stop it at the height of the cabinet over the sink?

kimiko232 -- I really like the cement tiles too; they are very cool. It remains to be seen if we are cool enough ourselves to pull them off. ha! Those California tiles are beautiful. I thought of diamonds but might just do running bond if I use 4x4's; there are only so many patterns you can do with square tile! One tile place showed alternating horizontal rows of rectangular and square tile, and that looked really nice, though a more modern look.

WindyCityLindy -- thank you! The wood countertop is kind of an experiment. :) I figure that at least the bottom course of tiles had better not be too expensive in case we have to change it out in a few years! (not planning to though!)

Ellendi -- yes, I wondered the same thing, if it would look less sterile/boring once all our junk was back on the counters. I really like blue and white (our dishes are blue willow); I think my challenge with delft would be to keep it from looking too country with the wood countertops.

Otislilly -- one of the tile showrooms had row after row after row of tumbled stone, so your comment made me smile (the sales guy there said the same thing). I think I want to go a little more retro/vintage in this house. Slate could possibly work, I'll have to look. Thanks for weighing in!

AnnieDeighnaugh -- I am wondering the same thing (i.e. bring in color with accessories) though in the past I haven't really accessorized in the kitchen; there is usually enough clutter to make accessories just more Stuff to have out. Of course part of the point of redoing the kitchen was to have places to put the clutter other than on the counter. :) Still, white tile would be a good excuse for a brightly colored stand mixer...

I think we will stop the backsplash at the bottom of the upper cabinets. I haven't checked yet, but from the comments the cabinet installers made, I don't think our ceiling is level from one end of the room to the other; so tiling to the ceiling might not look as good here as it does in other kitchens.

Thank you all for your help!

I like the 4x4 in a running bond idea. I recently ran a "backsplash thread" and I think that came out the winner. There are some other nice ideas there; check it out, linked below. Check out the pictures from the user melle_sacto.

One thing I am thinking of to add just a little variety is to use tiles with some small variation in shade. These can be expen$ive handmade ones, but I think you can get that look in less expensive tiles, too.

Here is a link that might be useful: Offbeat, vintagey patterns thread

Angie, I followed your backsplash thread with interest and I can't wait to see your finished product! Your kitchen is SO cool (love your cabs and stained glass and especially the b&w floor in your powder room). I like melle_sacto's kitchen very much too. Maybe it was marcolo (or pal?) who once said that white 4x4's were the closest thing there was to "timeless"; I do like the looks of hers in the running bond. Is that what you decided to do? Are you going to use a liner? I thought about it, and if I had a black countertop I might do a black liner myself. Melissastar's vertical herringbone is still on my list too though I don't have much excuse for it other than liking the way it looks. [grin]