Serves me right for not refreshing the page and seeing the photos...
Walls painted white would probably brighten up their bathroom, so they ought to be happy.
Next door should probably be consulted too, as you'd be applying a surface treatment to the exterior of their property.
As for the rest - various ideas, with different budget implications:
- Maybe the higher bit of concrete could be removed?
- Hardwood decking? A raised removable section at the foot of the steps would equalise the heights and give access to the drain cover if needed.
- Matching hardwood, or stainless steel handrail?
- Remove some of the back wall and replace with glass bricks?
- Remove the steps and replace with wood, thus opening up the space underneath to use for storage?
What's on the other side of the left hand wall in your first photo?