Trough Sink
If you have multiple munchkins, installing a trough sink in your childrens' bathroom will make tooth brushing and hand washing less messy. You may even want to consider hanging it slightly lower on the wall than the standard 30 to 32 inch bathroom vanity or provide sturdy step stools for your vertically challenged cuties.
Storage (and lots of it)
From baby thermometers and kid flavored tooth paste to hooded towels and bathtub toys, you are going to need a lot of storage space in your kids' bathroom. The beauty of open storage is that it makes it easier for your kids to put their own stuff away (eventually).
Hardware & Towel Hooks
The key to creating a kid-friendly space is making everything easy for them to use. Round knobs can be hard for little hands to grab, so consider D-shaped or cup pulls for their drawers and cabinets. Additionally, you will greatly increase the chance of towels being hung up properly if you give your kids towel hooks instead of towel racks. You can designate a hook (and its respective towel) to each child by displaying your favorite portrait of them above their hook.
Built-in LED Night Lights
Help ensure a trip-free midnight walk to the bathroom by creating a lighted path down the hallway with outlet covers that have built-in LED night lights.