I'm training to be a Civil Engineer, should be qualified next summer, so AutoCAD will take a back seat in my world.
However, during my training, and for a good part of my working life, I've used AutoCAD, starting with kitchen design, and now for producing the more basic deliverables in the CE industry. Civil3D will be more my gig, in fact it is already really, but AutoCAD will always be around, I think.
My thought process was that as I start doing less and less AutoCAD work at work, I could do some on the side, because when it's basic work, I do enjoy putting some music on, and cracking through some drawings.
So to answer your question: Civil Engineering, specifically Strategic Highways, but interior/kitchen design is also there too.