Robust input validation and help, sure. Never had a massive use for auto-complete. Maybe my console applications are just too small in scope. I write multiple programs rather than one program with "sub-operations".

I've always used the (rather dated) library NDesk.Options [0]. Even though it was written way back in the .net 2 days. For me, it seems to hit a very nice sweet spot between power and complexity.

[0]: http://ndesk.org/Options