Sounds like a Colonial Revival.
I'm well aquainted with those little vestibules. You're on the right track thinking of using small tiles for the floor. You can go with white, or with a pattern of earth toned colors if you like. Rusts, wine colors, greens, etc.
Generally for Colonial Revival I would tend to lean towards white, but of course, it depends on the other colors in the space.
the hexes or rectangles would be just right.

Hi, quite often you would see the vestibules tiled up to mid-wall height, with subway tile and chair rail and base moldings also in ceramic. The floor would be small unglazed mosaic. There could be a border like a greek key or other pattern, and there could be an actual mosaic "rug" in the center. It was popular to have the family monogram or last name inlaid, or even just the house number.
People often went overboard when decorating these spaces, as it was among the first things that a caller would see, and they were acutely attuned to making the first impression an overwhelmingly strong statement about their wealth/class.
Casey

I was talking to my mom this morning, so I asked about her vestibule to double check what she has in there. Her's is a 1907-08 era house with colonial revival styling. It was very modern and up to date for its day.
She told me she has tiny, white hexagonal tiles. As I recall, the vestibule has white wainscot to about shoulder height, with a heavy embossed paper depicting a shield with a fanciful coat of arms above.

Thank you both for your thoughts. I checked this week and my local tile store has some rectangular pre-made mosaic "rugs" that might work very well and and make a great 1st impression as visitors walk in my front door. But if that doesn't work, now I know I'm also on the right page if I go with the small hexes.
Thanks again.