The problem with making a wall you can get on both sides of is "Do I make the inside 'nice' and 256 units wide or do I make the outside the 'nice' 256 units" then the other is either slightly smaller, or slightly larger.
But this is pretty insignificant since most walls are either wood/thin metal and 8-16 units thick or concrete which can be a justifiable 32, making the dilemma practically disappear.
Don't worry about getting the Xunit wide texture fit perfectly, one thing that stops textures looking repetitive is unevenly sized brushes.
If you can see both sides of a wall corner, you shouldn't use a
butt joint but a
miter joint instead. This reduces the number of faces rendered as well as reducing the number of faces you need to texture (no to mention it removes the slight overlap where there is texture which could in more complex situations cause lightmap oddities)
It is important as a designer to understand a little more than the basics of building construction techniques and architecture since most of the time we're building buildings. (dohoh)
It looks to me like your stairs have a ramp under them even though the steps aren't triangular prisms themselves, here you have overlapping brushes, and more importantly overlapping faces on the edge of the stairs. Overlapping brushes aren't
too bad but should be avoided as good practice but overlapping faces should be avoided at all costs because 3D engines don't know which to render first which leads to
z-fighting So clip off the bottom of the steps so they're flush with the ramp below.