There are various design options for your walk in shower. One of the most common variations comes in the form of a glass enclosure, with the glass helping create a bright and airy feeling. For an even lighter effect, consider adding a window to the shower, if it is possible. If not, try a skylight. If neither of these is possible, an all-glass enclosure would be better because it remains bright enough even with artificial lighting only.
You can also opt for walk in shower designs without doors. Take a look at our bathroom remodeling ideas, compiled from our previous projects. You could have the other walls solid, glass-only or a solid base with a glass top half. One thing to note about the doorless walk in shower is that it does not allow for much privacy, and this is generally true for all walk in showers. If privacy is not your priority (or is already provided by other means) then a walk in shower is perfect.
Each design comes with its own logistical and construction headaches on issues such as drainage. So make sure you consider these when choosing what style to go for.