Selectively power peripherals on PCB
Cutting power to peripherals when they are not needed can definitely save power. But there are some things to be aware of.
First, if you have pins connecting from the main processor to the peripheral, all those pins have to be forced low or undriven when the peripheral is de-powered. If the lines have pullups, the pullups have to be connected to the same VCC that you are switching off. For this reason, it may not be practical to de-power peripherals which use I2C, for example, unless you are de-powering ALL of the I2C peripherals at the same time.
On boards with a VCC plane, using switched power can complicate component placement and routing.
Some peripherals require configuration or initialization after they power up. And the driver code on the host processor may not realize that the peripheral has lost its configuration. So there can be some software complication involved in re-configuring a peripheral each time power is cut and then restored.
None of this is intended to talk you out of it. These are just things to keep in mind.
I have done this before, but usually I don't use a dedicated load switch IC. I just use one or two MOSFET's, depending on details.