The wall tile is ceramic, the shower floor is tumbled travertine that comes in a 4 x 4 format. Please let me assure you of something-travertine is NOT a high maintenance product! I am not sure at all why some people give others , like yourself, reason to doubt their decision based on that. We have completed over 45 travertine showers this year, three times that in the three years we have been in business. No maintenance issues EVER. In fact, my clients say the exact opposite! Travertine showers only look better with time, in my opinion.
We don't customarily seal the showers after installation, but some customers choose to do so on their own for different reasons and I think sometimes people get hung up on that-they think they "have" to seal the stone and the grout and maybe they assume it is a big job. It isn't. We use DuPont Indoor Tile and Stone sealer from Lowe's- I always apply at least four coats because I prefer the way it makes the stone look. I reapply once a year. All you have to do is "paint" the sealer onto the surface, wait for it to absorb and wipe off. How easy is that?
I hope this helps, please do not hesitate to contact me if you have any other questions! I suspect that you will LOVE how easy the maintenance is on your new shower and enjoy it for many years.