This is a WONDERFUL addition to any steam room and is highly recommended regardless of size!
The #1 benefit from adding glass to your steam shower is that it enhances the thickness of the fog created in the environment. Many people don't realize that steam is clear and that it is the hot steam meeting cooler surface materials which creates that rich fog so many people expect.
Adding glass also allows more light to enter the shower, makes smaller spaces seem larger, and adds many unique design elements. From glass walls to glass block to double pane exterior windows or skylights, the more glass, the better!
The key factors to consider are effective insulation and accounting for the heat loss when sizing the generator for your environment. I would suggest that you call a Steam Bath Specialist
to discuss your options, what you would like, and any further questions your contractor may have.