The improvements to 2D layouts and outputting in Rhino5 are great, but there are two basic things that could make the drawing process a lot easier.
The first is stacked fractions. Currently the only way to make fractions is with full-font-sized numbers. This is awkward to read and a big waste of space. A stacked fraction that takes up the same amount of space as one full-font-sized number would be great.
Also, there is currently no elegant or easy way to make running dimensions. I do some drawing for fabricators, and they want to be able to lay down a tape and mark off dimensions, rather than having to add up each previous dimension, which is an extremely error-prone task.