When considering a renovation of a master bath or Mother-in-law suite, A curbless walk-in shower should be feature to consider.  Not only do they look appealing and give a more open feel,  they will also ensure the ease of entrance as you get older.

Curbless entry for Walk-in shower (SRW Work)

There are many new systems and ways to accomplish a curb-free entrance to a shower without creating an overall height issue with the rest of the room. My favorite system to date is the AKW Tuff Form shower system. It is a preformed shower pan for a tile installation. The great and easy thing about the "Tuff Form" is there are no alterations needed to existing framing. So if you have a newer home with engineered floor trusses or engineered joists this would work perfectly and keep from having to raise the rest of the floor height. Here are few pics of the installation (all work completed by SRW Contracting Inc):

Plywood is removed in shower area and additional framing is installed for support

Waterproof membrane installed throughout entire room and flashed up walls in shower

Black Slate curbless shower

Pebblestone shower floor 

A channel drain is also a popular design. It  Requires alterations to framing, a mud pan, and a bit more work to waterproof, but gives a great overall look and allows for many more options with tile (can go with larger tile than the standard    2" x 2" required for most other systems)

Alterations made to framing for channel drain

Mud pan base sloped to channel drain

Waterproofing installed for curbless entry with channel drain

Curbless shower with channel drain

Life can throw many curve balls at you.... If  you are renovating a bathroom because of a disability, having trouble getting in your current tub and shower, or you are just simply planning ahead, a curbless entry shower is a great option to consider.