I've moved: Please see my dramatically improved site: RetroRenovation.com
It was very difficult to find tile in the correct 50s shades. My best source: A Canadian-based company, Olympia Tile, had a selection of 4.25 x 4.25 "Maple Leaf" tiles in appropriate shades. Good news, their distribution network in the U.S. is growing. Go to olympiatile.com to see where you can buy this tile. No photos online - watch this site and I'll post my bathroom pics at some point.
Colors I used in my bathrooms: Heron Blue and Fawn Beige. I used the 4x4s for field tile and for edging, trimmed them with a basic United Ceramic white 2x6 from Home Depot. I used Olympia's matching 2x6 cove base to meet the walls with the floor. Note, we installed the cove pieces flush with the floor tile (rather than 'sitting on top of it' -- but struggled because the room was not perfectly square (by a long shot.) This is a trade-off decision.
Other colors I like in the Olympia line: Primrose (yellow), Teal Blue and Lake Blue, Salmon (would be great with black or grey trim) Terra Cotta, Bone and four shades of Grey - Thunder, Platinum, Silver and Tender (my favorite.)
This tile was all very inexpensive. Note, I bet you can go much higher-end -- to a Waterworks or Ann Sachs -- and probably get a better selection of colors. However, this will be at a much much higher price.
Finally: For my floors, I used American Olean Chloe, a "pinwheel" pattern evocative of the 50s, with the gloss black dots in one room, and with plain satin white in the other two. To be honest, I prefer the all-white. Use warm grey sanded grout -- it's a nice look. You must seal the grout, though - an arduous (but worthwhile) task.