Bathrooms occupy relatively little square footage but can consume enormous amounts of money and mechanical complexity.
You need a logical public bathroom near the main living and entrance areas so guests do not wander into private bedroom zones.
The primary suite needs its own bathroom. Secondary bedrooms may each have ensuite baths at higher price points, or children may share.
If children share, think about simultaneous use: separate toilet, multiple sinks, shower access.
At least one bathtub in the house is usually sensible, especially for children and resale.
Do not confuse giant showers with good design. Some become larger than bedrooms and contain so many shower heads that water pressure, drainage, and hot-water capacity become real engineering problems.
Group plumbing where practical.
Back-to-back bathrooms, stacked bathrooms, and proximity to kitchens, laundry, and water heating can reduce pipe runs and simplify construction.
Waste plumbing needs slope. Extremely long toilet runs are possible, but they complicate elevations and underground work.
Hot-water distance matters too. Long runs waste water while you wait for heat unless you add recirculation or other systems.
Bathrooms should not feel like leftover spaces squeezed into the plan.
Spend finishes according to the house and avatar. Bathrooms can range from modest to extremely expensive based largely on tile, stone, cabinetry, glass, and fixtures.
Good bathroom formulas already exist.
Use proven layouts, then spend creativity on materials and details rather than inventing inconvenient plumbing experiments.