Curb or curbless
A low curb is simpler and cheaper. A curbless entry needs the floor recessed or built up. However, it is worth the extra if you plan to stay in the house.
Glass, or no glass
A frameless panel looks better and shows every water spot. A walk-in with no door at all works, but only if the shower is deep enough that spray never reaches the opening. Be realistic about that dimension rather than optimistic.
Drain and slope in a walk-in shower installation
A linear drain lets the floor slope one way. That makes large-format tile possible, so it is the usual choice for curbless. A centre drain needs the floor to fall from four directions, which limits tile size. Decide this before you order tile, not after.
Ventilation
In this climate a shower without a properly vented fan is a mould problem waiting, and the EPA is blunt about why. The fan must discharge outside the building, not into the attic, which is the most common defect we find.