I've gone with a greige neutral tile and a decor pattern (all same shade but geometric textured design) in the back of the wall where our walk in shower is. It's a very neutral scheme. My last bathroom was old when we moved in but it lasted another 17 years before forced to change it due to leaking. That was a neutral peachy shade with a little bit of more dated border but nothing too bad and it remained acceptable. I doubt the (lovely but) garish tiles that are currently the fashion will last as long.
I have a very simple walk in shower now rather than a cubicle. Much easier to keep clean. Less movement in the shower tray than the previous one (less chance of leaks).
My bath is j shaped so to miss a corner off and improve space / access to sink.
I have 2 drawer storage below the sink. It's all very well having a beautiful rustic sink but soft close drawers and adequate storage go along way in your average family bathroom. Things get lost at the back if you have shelves.
If you can fit in a wall mounted narrow cupboard that would be good. I just went for a mirrored cabinet with a small shallow cupboard behind it. I didn't get it with electric hook up as I've known too many people struggle to get the right bulbs eventually or just CBA to fix it so it stays broken. A lit mirror could have been nice though.
I put a compact shower unit onto my bath as well as separate shower. I has one originally and find it useful for washing my hair when in the bath and for cleaning the bath.
Mine is very featureless because its all tiled. The trend for a mix of plaster and tiled areas does look good and can be done as neutral but interesting / bit of texture. Maybe invest in a really good extraction fan if you are concerned about damp plaster but like the look. It means you can paint to change the look over time. I just wanted a bathroom to last.
I got "fit and forget" good quality fittings. Get a good, well recommended bathroom fitter and take their advice. You want plugs that are not faffy and won't break, reliable taps (groehe in my case) and as high a quality shower as you can afford. I went mira as my last shower was mira and was easy to replace parts. Sadly the old mira shower was powerful and the new one is not as good.
Worry less about look and more about practicality.
There's some lovely tiles about. Metro tiles are ridiculously popular right now. Obviously they will date but such is life. I actually put some cream textured ones as a small splashback in the downstairs cloakroom. I like the white /cream/ rustic textured ones to and my bathroom fitter said very popular right now. The teal / green shade is especially popular and ubiquitous right now but I think its going to date more than a neutral scheme.
Try porcelain superstore for tiles. They had some lovely ones. The prices were good. They send beautifully packaged whole tile samples
Avoid gold taps or black taps. The colour wears off. If you don't mind replacing them after 5 years that's OK. Some people like the look (it looks great at first but once worn looks tired and tacky).
Long post. Hope this helps!