If you want to get some experience with closer to commercial type Linux (you mentioned setting up in an office network), I'd probably go with the Redhat family. You can start with Fedora (more consumerish flavor), then/or Centos. Both of those are free, and from Redhat.
Centos is quite close to "real" Redhat, that you'd see in commercial installations.
We run 100s of Redhat Enterprise servers, but I do my development on Centos. I also have a couple of Fedora instances for my personal use, because Centos doesn't always has drivers for newer hardware.
At least in the space in which I work, we rarely see any other Linux, except possibly Oracle's Linux, and maybe Ubuntu once in a while.
I think that pretty much any distribution has a LiveCD that allows you to boot the CD (or DVD) so that you can get a feel for the environment.
Another approach you can take is to use something like Vmware Player or VirtualBox (both free) and install whatever Linux distribution(s) you want as different "guests". That way, you can try different ones, and go back-and-forth as you please. All of the Centos and Fedora stuff that I mentioned are running like that, either under VirtualBox or under Vmware Workstation (at work, under Vmware ESXi).
P.S. Your question is not 'off-topic' here, as this is the 'off-topic' area of the forum