Below are product recommendations for specific bath & shower cleaning issues. 

For general or daily shower/bath cleaning the Stone Care: Soap Film / Hard Water Remover (1 QT) is the best product.
For cleaning mildew, specifically you'll need the Stone Care: Mold & Mildew Stain Remover (1 QT) which safely removes bathroom mildew without damaging natural stone like common cleaners.

However, there could be more to consider regarding a mold/mildew problem. Several contributing factors can result in the development of shower mildew. Using the appropriate cleaner is only one part of the equation. For a detailed explanation and solutions for shower mildew issues please read:Cleaning Marble Tile Shower Mildew.

The Stone Care: Bath & Shower Kit includes the Soap Film/Hard Water Remover, Mold & Mildew Remover, a Neutral Stone Cleaner for countertops and a shower squeegee.

The SCP: TOILET BOWL CLEANER is perfect for safely cleaning toilets set on marble, travertine or limestone floors. Standard toilet bowl cleaners are very caustic and will etch/damage marble when spilled or splashed on the floor, etc.

To improve safety on slippery floors, SCP: ANTI-SLIP Floor Tile Cleaner (gal). 

The problem with soap scum is that it is very tenacious and cannot be cleaned or removed with ordinary cleaners. So, after "cleaning" the shower you'll still have a smooth and even layer of soap scum present. Very often, this whitish film can go unnoticed especially on lighter-colored tiles. It builds and builds until finally you notice the tiles just seem very dull or washed out when once shiny or more vibrant in color.

The product formula for cleaning mildew vs. soap scum is very different, so there isn't an "all-in-one" solution. Mold and mildew should not be a constant problem. If so, then steps need to be taken to correct the cause as noted in the article link provided above. So, the Mold & Mildew Cleaner is a product designed for periodic use when mildew is present and for more rigorous disinfecting purposes.

The Bath & Shower - Soap Film Cleaner, however, is the product designed to be used as a daily or regular shower cleaner and is the most effective product for keeping it as clean and disinfected as possible.