. I appreciate working with the age and style of your house, but I don’t think you have to automatically cross off ‘modern’ for an older home. During our travels in EU last year, we stayed in several Airbnb’s in VERY old buildings, with modern kitchen & baths. It was quite striking. I think it is more important to not choose something currently in vogue. I think that would date your choice more quickly than something clean, simple, and elegant.
If you have a Floor and Decor store near you, that is tile heaven in reasonable prices. You can buy a million samples and return them. They also have a design desk. But I would narrow down your favorites before working with them.
First you need to decide the bling or accent tile you are in love with. Everything can build around that. Large 12x24 tiles on floor are a contemporary or updated style. Shower floor needs to be close to a 2x2 for safety. Shower/bath walls can be anything, including very large to minimize grout.
To reduce any issues with grout getting dirty or stained use Mapei grout or epoxy grout
Several years ago (time flies) we redid our current house. I researched tiles and found some sites which explained various important factors. One is definitely the slip factor/coefficient- when wet , not just dry. Google choosing tiles. You will find some good info from some store websites, even if they are not in your area (and not a purchasing option). One thing I goofed on, and had the contractor fix, was sharp tile edges. That’s another factor to learn about.
Quality- ceramic versus porcelain may not matter. Wall tiles are very different than floor use ones. The shower floor will be small tiles but the main floor is where you don’t want to step on tile borders with your bare feet.
Consider the overall color scheme- grays or beiges is the major one. Be neutral in floors and wall so you can change the décor. It is a lot easier to change wall paint colors than to be stuck with something that goes well with that interesting stripe/design color. I personally dislike subway tiles.
And be prepared for your choices to outdate next year. Choose what you like, not what is in fashion while keeping in mind changing towels et al in the future.
I don’t like any color in my bathroom other than white and tan, maybe black for accent. I have never thought of using grey. I don’t really think neutral colors would go out of fashion. There are some designs that are timeless.
“We visited Galleria and TileAmerica stores and after looking at stone and porcelain tiles, we opted for porcelain, which does not require sealant or special care. The tile we chose for our bathroom floor and our curbless shower walls and ceiling was Carnevale porcelain tile at TileAmerica. The color we chose was Grigio (gray). I find this tile very easy on the eyes. I’m happy with our choice.”
I chose something very, very similar. It could be the same for all I know. Don’t remember the name only that it is Italian porcelain. We did a complete gut job and put this tile all the way to the ceiling around the tub, in addition to the floor. I used the same tile for floor in powder room, too. I love, love, love it. I worked with a designer and didn’t pay attention beyond picking out what I liked and what worked with the vanity’s wood, granite and marble I chose.
We went for a gray and white tile (it isn’t uniformly gray) because I don’t care for warm colors for a bathroom, and it went well with the color of the cabinets and paint we liked. I was less fond of porcelain tiles that looked like marble. But that’s just my taste.
We did find a wider selection of warm colored tiles (tan, beige etc.) than cool ones, though.
We had tile similar to what mathmom describes in our House1 MB. Grey Italian porcelain, large tiles. Big ones on the floors, slightly smaller for bathtub surround and shower walls. It was installed 19 years ago, and it looked very good even by today’s standards. Neutral does not go out of style. 
In House2, we have a combo of dark brown granite and beige limestone tiles installed by previous owners. I don’t particularly like it, but it is solidly built and has held up well. I don’t think we will be renovating that bath any time soon other than installing new vanity mirror$$$.
We went from gray tones to beige tones for the change. The new owners of our last house now have “in” colors with the “tender gray” and whites for facilities. Maybe by the time we are ready to move our current colors will be in. Had asked our realtor six years ago but in current area he said it doesn’t matter- do what you like. The major thing for me is being able to choose wall paint and towels/rugs that we like and work with the permanent (for us) tiles. I ignored some gorgeous tile accents that would have limited color schemes.
Keep the tiles neutral and use other color accents. Also consider what you want to stare at day in and day out as you use the facilities. Plus ease of upkeep, counter space, storage. We went with Corian with integrated sinks- no grunge, easy to push water into sinks, softer than stone. I’m practical and thought of cleaning.
Oh- and did honey colors for cabinetry in both houses. Back after finally took my shower- I actively like my colors and styles, although would tweak the bath floor. They always seem to introduce something you like better just after you do the job, sigh.
Thanks for all the ideas!
I’m keeping my eyes open and seeing more tile places around. Once we get D18 settled at college this week, I’ll have to start making the rounds and see some tile in person.