Asking for "more" during office hours? In some good classes I've had, I've gone to office hours not because I'm confused, but because I just want "more". I like the teacher and just want to listen to them talk about whatever, even if it's not necessarily about the class. I can usually come up with a couple questions for an excuse to come by, but I wish I could just say "please teach me more".

How do you do that? I don't know how to ask that, or how to instigate it. I usually just try to ask questions but sometimes I honestly don't have many, or at least ones that couldn't be solved by using a book. Usually these classes are ones I like, and thus I try to keep on top of things.
I am not sure what you are looking for is possible. When I was first getting into research, there were plenty of people I thought just had amazing things to say, and great perspectives on so many topics.  Even after school and being in research, there are people I truly respect that have a unique perspective on much of academia.  The issue is, these people are usually respected by more than just one person, and as such, are extremely busy.  They are also the people who are invited as speakers to conferences, TED events, etc.  

My suggestion is, if you are really interested in hearing more of their perspective regardless of it being a topic of your class, you can ask if they hold other classes in which they lecture.  Additionally, you can easily look their name on google to see if there are conferences they have given talks on (which is highly likely if they are a top academic).  If you can not find anything online, you could still ask them if they have talks available online in a respectable way, such as:


  I really enjoyed your explanation of topic x, it was a way I had not
  heard it explained before, do you have any online resources in which I
  could hear more of your thoughts on this?


If you are not interested in watching recorded talks, and only interested in one-on-one communication, I think you need to think more about the comments to your question by seeking more specific questions, or your real issue with wanting to hear the person speak.