Is there any benefit of using a VPN on both the host and guest when working with virtual machines?

It is better to run it on the host so the VPN itself and the connection to your actual IP is isolated from whatever activities you do on your virtual machine.

/u/TobiasRieper is right, adding more complexity does not necessary improve your anonymity. However, if you choose VPN-servers in incompatible jurisdictions, then a double VPN can be worth it. However, if you do this, I suggest that you have the VPN in the host and in a physically separate gateway / router to ensure that a malware in the host don't reveal your real IP.

EDIT: This comes with a network latency penalty, when using real servers in incompatible jurisdictions the latency will increase significantly, and with Tor on top you will have 500-2500ms latency. It's not workable in all cases.

Just run TailsOS on USB. Not whonix or tails in VM.

Tor isn't a VPN.

The user didn't say anything about using any of those OSes.

Running one multi-hop VPN on the host is more realistic.

You're right. Tor isn't a VPN, but it's essentially the same thing from a non-technical perspective. You want to access a webpage, but you send all requests through a middle-man first. I didn't think it was a distinction worth making for a quick reply as the are abstractly the same thing.

my fault I was just assuming they might have been referring to whonix over linux or worse windows

Issue is that one is exactly one. And remember "Trust no one, especially not your self". So, depending on your threat level, you might need to alter your internet connections in curious ways.

Not the host, unless you're crossing pastes or something. You want bridge, not nat. If you nat, it's sharing the host ip protocol, which means you've flipped priority and the host should be on the vpn. Think of a vm the same way you do tails, the only difference is you have to remove/delete the vm after use (as if it were a usb). With a vm you've got one extra precaution--making sure no one gains access to the host machine (in tails there is only the vm, so to speak).