Over the past few years my wife finished off her Sommelier diploma "in her spare time" (she works outside the food / wine industry for her day job).
Obviously she learned a ton (and ended up working part time at a wine store for a while), but more surprising was that I learned
a huge amount as well. I never considered myself a huge wine fan (just beer and spirits!), but after participating in a lot of the tastings that she was doing, my enjoyment of wine started to really increase.
She took the ISG program (https://www.internationalsommelier.com/
) and completed the sommelier diploma program. The ISG program seemed to focus quite a bit on restaurant planning and serving as well as the actual aspects of wine. The course material mainly covered wine, but they did receive basic knowledge on spirits; most of us here would have better general knowledge about whisky and other spirits that we enjoy, though they obviously covered spirits in a structured manner.
While doing the ISG program, she found out about another program called WSET (http://www.wset.co.uk/
) which stands for Wine & Spirits Education Trust. The cool thing about WSET is that it - apparently - aims to be a little more global in its reach (whereas perhaps the ISG is a bit more N. American oriented - not in wine - but in course structure and relevance). Anyway that was the feeling that she got.
Anyway - to get to my long overdue point - WSET offers courses in spirits. The other cool thing about WSET is that the courses are modular, so you can more or less take what interests you if you're just taking them for general knowledge. I'll probably take one or two of their spirits course just for general knowledge over the next year or two.
Hope that helps - cheers!