Separation preview with values on hover
Just like in InDesign there should be the value of each channel on the exact spot (while you are hovering over any point on your artwork)
Here the difference between AI and ID (each while hovering over an image)
It's hard to check color values without (at the moment you have to put the finished .ai into a InDesign document, activate separation view there and check each point.) For printing you have a minimum requirement of 3%-7% (depending on the technique like offset or gravure printing) in each channel to make sure it actually prints. Otherwise it may not! It would be also useful to check whether your black is just 100% Black and does not consist of any other Channel. Finally to check if every black is overprinting.
Yep, that's all only possible in InDesign (or Acrobat) but not in Illustrator itself