You will never go wrong with white fixtures and white ceramic tile in any size. Cheerful, bright and never out of style.
Use darker tiles on the floor, but not too dark (shows dust and water spots), not too light (shows dirt), not glossy (too slippery), and not too uniform in colour (shows dirt) .
Make sure the absolute straightest framing lumber possible is used under any surface that will be tiled. Perfectly flat surfaces are the key to quality tile work.
Always use smooth and glossy tile in wet areas. Easy to keep clean.
Never use white grout. It never stays clean.
Ensure that grout lines are as tight as your tile person can manage. Never larger that 1/8". Anything larger looks dated and will get dirty faster.
Use the largest tiles you can in the shower area. Minimizing the number of grout lines is the key to a shower that stays clean.
For the shower floor, don't reject white fibreglass or acrylic shower bases out of hand. Tiled shower floors look great but never, ever stay clean very long. A fibreglass or acrylic base combined with nicely tiled walls and a custom frameless glass enclosure looks just as custom as an all-tiled shower.
Never use tile on the surface of a shower seat, on top of a shower curb, or to frame a shower niche. Always use a solid-surface materials (marble, granite, man-made quartz, etc., custom-cut to size) which present no opportunity for water ingress.
If you use marble in a bathroom, remember that it will always need periodic re-sealing to maintain water repellency (almost everyone forgets this).
Take cure to ensure that silicone caulk is absolutely perfectly applied to every inside corner of a wet area. Even the slightest gap or bubble can lead to water infiltration and mold formation in short order.
Make sure there is a 1" gap under the bathroom entry door or the bathroom ventilation fan will be unable to draw in enough replacement air, and you will get steam and condensation everywhere.
Use wall-mounted vanities in small bathrooms to increase the sense of floor space.
Buy your vanity and make sure it is on-site before any framing or plumbing work is done. Some vanities require structural reinforcement behind the wall, or have drawers and shelves in locations that could interfere with drain and water supply placement, and your framer and plumber won't know where to put them unless the vanity is on-site.
If possible, buy your vanity mirror(s) and have them on-site as well so that your electrician will know exactly where to place fixture boxes above or beside them. This is especially important with double-sink vanities where knowing the exact distance between the centreline of the sinks is key to placement of light fixtures above them.
Body jets in a shower are a waste of time and a source of amusement for about five minutes. A hand shower mounted on a flexible hose is vastly more practical and all you need.
Install a heated floor if you can afford it. You will never regret it.
Always install a recessed light fixture in the tub or shower area. You need light here, plus it highlights nice tile work.
Don't mount a recessed light directly over a toilet. You don't need to highlight what goes in here.
You don't need to spend a fortune on shower controls and sink faucets. Every well-known mass-market brand is good quality, and some carry lifetime warranties.
Here is a bathroom (in a basement) that has most of the features noted above, will last almost forever, and unlikely to ever look too out-of-date:
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Pony wall
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