I understand you are small and need to get a little more growth out of your workers so you can invest in your core. This is double edged, but I will no try to disuade you.
There is an excellent online learning site called Lynda.com $300/year per employee and you can create custom learning playlists for them to build their skills from nearly all of the Microsoft Certification Exams/Linux/Opensource. In fact, if you want to give them a bonus for getting A+ certified, they have a learning path for that as well. It covers nearly every topic from systems administration to advanced excel to could computing.
I used it all the time to train myself and train up developments teams. I mean, do you know how to write python app so that you move it to a Heroku container in Amazon Web Services and horizontally scale it as big as you need to? Well Lynda has a class for that. :)
Here is the trick. PICK A CORE PLATFORM AND TOOL SET, or you will have eventually have a mess beyond belief as people cycle-in and out. If you don't limit the tools and just tell people to learn stuff, they will, and eventually you will have experts in an unsupportable disaster. You don't want this. Chose your platforms and tools, then give people a learning path and incentivize them. Use Lynda.com.
THat is all.