This is slightly off topic but I am curiuos why you need virtual machines on a nuc. I haven't found a lot of usage for virtual machines to date yet i hear a lot of other folks use them right and left so I am curious why someone (or how someone) would use multiple virutal machines. I can sort of understand it for running windows software on a linux machine (more efficient in some cases than wine) or for having a super powerful machine (blade) for large organization to share but a nuc doesn't really fall into either of these categories when you talk about multiple vms.
In my particular situation:
1. I work in a tiny cubicle. The more space I can free up, the better. I don't have the room on my desk for a tower PC, and I was constantly kicking the tower underneath my desk.
2. The NUC platform is powerful enough to run several reasonable virtual machines. Core i5 (dual-core + hyperthreading), tons of RAM, fast SSD, high-speed USB 3.0 ports. It's not a CPU powerhouse, but it's enough to get the job done if you don't go nuts.
3. I prefer running my work computer in a VM for a lot of reasons. First, if something crashes, it only crashes my VM, not the host, so I can keep working on other things while I reboot the VM. Second, snapshots make backups really easy. If something breaks or I get a virus or whatever, no hardware is involved...just roll back to the next snapshot. Effortless.
4. Useful for burner VM's...opening potentially unsafe files to test for viruses that people got say via email in a workplace environment, testing out new software & updated revisions or Windows update to see what is affected & what breaks, that sort of thing. Rather than having to have physical hardware to do that, you can test stuff out, then just rewind to the last snapshot to start fresh again. One click disables network access if you need isolation. You can direct-connect USB devices via host pass-through in a VM. Lots & lots of applications just in this one area alone.
5. Testing VM's...use a VPN to see what things look like from the outside of your network. Run different OS's, updates, browsers - especially good for web design. Again, lots of use-case scenarios here...kind of depends on what you want to do.
So I have a tiny, quiet box mounted underneath my desk (out of kicking range), not taking up any space or power, with a nice, safe host OS, and several VM's that are protected with snapshots that let me do a lot more work, faster, and concurrently. All in a package about the size of a two-pack of Hostess cupcakes. As far as using a Linux host goes, sure, but Windows installs in minutes via a USB stick (or clone restore), has easy drivers, easy setup & configuration, the most compatibility, and lots of security software available for the host as needed (easy-to-configure A/V, firewalls, etc.). If you want, you can go crazy with firewall rules & lock down everything on the host so only VM NAT traffic gets through. And then clone the host using a Ghost-like program to make sure you have an extra copy of everything. Makes life sooooooooo easy.
I have a powered multi-port USB 3.0 hub on my desk for the rest of the stuff as needed...8TB backup drive, USB readers (floppy, Bluray/DVD/CD, IDE, SATA, M.2, mSATA, etc.), that sort of stuff. Combined with a quality toolkit (iFixit has great ones for under $100), some cleaning tools like an electric "canned air" machine & electronic cleaning wipes, label printer, etc., my overall computer repair center has really shrunk down quite a bit. Everything fits on my desk & in a couple drawers now. On a big UPS, the NUC & LED screen lasts, like, hours now when the power goes out. This setup basically lets me do nearly everything I need to do on a daily basis as a computer tech. Pretty nice!