yes, i am a heavy user :P

i dont have a second monitor atm so i use'em all the time, and tabs also.

Yes, I use them. At work, that is. 3 are generally occupied by mail client, terminal, openoffice calc, eclipse and two openoffice writer windows.

Yes - web browser, terminal, mail client and office.

I have used this setup for a few years now so I still have not been able to embrace Gnome 3. I use Cinnamon under Fedora.

I never use them but since debian jessie, with XFCE I keep hitting arrow key & switching desktops I think I'm going to start.
It seems faster than minimizing or resizing windows

They both do different things. Multi monitors are great for having visibility of more programs at once. they allow for comparison and copy-and-paste between applications in a much easier fashion than having to tab through applications or desktops. If, back when I did Windows admin at work, I had the possibility of using virtual desktops I would still not likely have used them as anything but multiple monitors would have slowed me down. We all, from helpdesk to developers to various administration teams all found our productivity went up when we gained extra monitors and I don't see any way that virtual desktops would do the same.
I do see why people would use virtual desktops, by the way, but they're not a substitute for real monitors.

I've done a lot of work in the VDI & PCoIP space with Linux and Windows. Windows VDI, and Linux blades in datacenter with PCoIP cards. And zero clients in the office. I'm not sold on it, quite frankly. There are so many problems, from single sign on, to resolution issues etc.... VDI works ok, depending on the brokers you use. We use Leostream, but there are others.

Mac mini's on the desktop, now there's a solution.

I have a wide screen monitor, so I can just fit both of them to the screen and view them side-by-side.

Whatever, I'm not saying you shouldn't use multiple monitors, I'm just saying I have no use for them and no room for them either.

I rarely ever use them, I'm more comfortable with just one desktop.

I rarely use a different desktop. The only exception is anytime that I am using my computer and my daughter wants to use it for a minute. I switch to the second desktop where she can open programs and close them.
When she is done posting "Carrie knows Mark is going out on her because Misty spent the night at Laura's house and they went to the park and saw Mark holding hands with Jennie and they told Carrie and, like... OMG" on Facebook, I go back to the first desktop where my programs still are - undisturbed.

I am running Gnome Flashback under Ubuntu 14.04 and have the workspaces preference set to 12 (maximum is 36). For a long time, I used Unity under Ubuntu 12.04 and had the workspace matrix set to 8X8. I never actually used all 64 at once, but I did use a lot of them, usually with one application per workspace -- only one per because I found Unity's app switcher within one workspace inconvenient to use. Eventually I went back to Gnome, where I find it more convenient to have several apps open in one workspace.

I don't see how anyone gets along with only one workspace.