I have a seashell limestone floor in my kitchen (from Mandarin stone) laid in a opus pattern, I sealed the tiles front and back with fila fob, and then waxed them twice using fila satin wax, since then (18 months fitted) I just clean them using a mop and a bucket of water + a bit of wax, and avoid detergents.
Looks really really good, mind you the kitchen is 32 sqm so its a reasonable size.
I didn’t laid them myself as I chickened out out it as at 32 sqm in an Opus if it started to go wonky it would have been a lot of materials to waste, so I paid the £400 and let some else spend 4 days getting it just right.
I would avoid travertine as they are full of holes due to the nature of the material, which isn’t great in kitchens