Let me join on this XFCE love fest. I also think it rocks, but it's more than that. It's also my go-to install for "friends and family" linux installs (Debian stable and XFCE).

I've been doing a couple of these over the years, and the great thing about XFCE is that it doesn't change, while at the same time being fairly intuitive and discoverable to the tech-unsavvy people.

So, with XFCE, I explain things once and I don't have to explain things to that person ever again. It stays as is over the years!

One only have to make sure to disable the virtual desktop (4 screens by default) thing and be sure to only keep one. That's the most confusing thing to non-tech-savvy that ever was. "Where have all my windows gone?! I moved the mouse and poof! they were gone"

Also, it runs great on old hardware. It's mostly what I've been doing. Family and friends tell me how they'll need to buy a new computer because theirs can't go on the internet anymore. I tell them "no you won't!". And then their computer becomes super fast again. Make my Computer Great Again.