Room décor is a tricky art. There are no set rules. What works in one context might clash in another. Perhaps the meta-rule is that all the pieces must fit together.
In the past, and in some cultures, it has been fashionable to cover every part of the walls with immaculate detail. Today this is considered a cluttered and overcomplicated look. Yet a moderate amount of detail, or detail that has some sense of order, can be a very appealing in many contexts.
A feature wall is one example of this. This is where a single wall of a room is strongly decorated, with surrounding walls kept quite sparse. When done well this can achieve a pleasing balance of openness and complexity.
Tiles can be effective for a feature wall. Mosaics are one example of this. Though they require a considerable amount of pre-planning mosaics can give very artistically pleasing visuals.
Tiled feature walls are more likely to contain simple patterns or tiles with images. Patterns can be stone or woodgrain, which are fairly unobtrusive. Or they can more complex geometric patterns. Textured, three dimensional patterns are also good in many contexts.
Tiles work well for flooring in many situations, especially with bathrooms or other areas that are likely to get wet. Sometimes a wall may repeat the same pattern used on the tiles floor. Else, a feature wall might work with a different pattern. Plain tiled floors can work well with a strongly patterned wall. Large mirrors can also be good in this context.