I am not a tile expert but I do know that Daltile has a porcelain tile in there Florentine series that mimics Crema Marfil. They have 24x24, 12x24, 12x12 and 2x4 brick joint mosaic in a matte finish. They have 12x24 and and10x14 in glossy finish.
I have not seen the Crema Marfil in person but my DD just had their Florentine Carrara installed in her bathroom. Her tiler thought the tile was a very nice quality. Everyone that has seen the installed tile thinks it looks great. Maybe the Crema Marfil would work for you if it can be cut to the sizes you want.
Just in case you are interested here is what the Florentine Carrara looks like in her bathroom.

And here is a picture of the Crema Marfil from Daltile's website

Badgergal, your daughter's bathroom is stunning and seeing the tile laid in a stacked layout is very good-looking.

I hope that bill_vincent, mongoct or Stonetech will confirm that an 18" square porcelain rectified tile can be cut in half so that it can be laid in a herringbone pattern. I'll look for the Daltile crema marfil tile and I appreciate that you provided the suggestion and the link.

Thanks.

Bump----hoping to hear from the tile experts!

You can try to find 9 x 18" porcelain tile with the travertine look.

Look for Enduring's herringbone thread in the bathroom forum. Mongoct gave her several posts from cutting them (which she did) to how to figure out the pattern. Good luck.

IowaCommute, thank you very much for the suggestion. I found the April 6, 2012 thread about cutting enduring's slate tiles and mongoct's detailed layout instructions. Very helpful! However, my understanding that natural stone tiles, including the slate that enduring was using, is a good product to be cut and that the cut edge will look fine. (I did this on the travertine tile we used in our laundry room.) However, some of the tile sales people tell me that cutting rectified porcelain tile produces a cut edge that is not acceptable. I've not found a rectangular floor tile that is 9 x 18 or 6 x 12 that looks like travertine or other stone. I have found 18" square porcelain throughbody rectified tile that I hope can be cut in half to produce the 9 x 18 tile I'd like to use for a herringbone pattern.
I am hoping that the tile experts will assure me that the tile can be cut and look fine. Or, if anyone knows of a source of rectangular porcelain floor tile that looks like stone, that would be great, too.

Here is one for you in 9 x 18".

Try typing "9 x 18 Porcelain Travertine look" into a google search and you will get some hits.

Here is a link that might be useful: Florida Tile

jerzeegirl, thank you. I found this tile but the 9 x 18 is only for wall use, not floor.

Yes, it can certainly be cut to the size you need. "Dressing" the cuts with a "rub stone" will break any sharp edges and, with the grout installed, there should be absolutely no problems with it.

Thank you so much, StoneTech! I can find many 18" or 20" square tiles that I like so knowing that they can be but in half and "dressed" should work.

What do you think of having 10 x 20 inch tiles laid in a brick pattern with a 50% overlap? Will lippage be a problem?

Nancy~ It all depends on how flat the tiles are. If they're "perfect," a 50/50 overlap should be good. If they're "bowed" then a 1/3 overlap should be used to eliminate any lippage.

Pictures, we need pictures!