This is the setup I (used to) use. My monitor doesn't do usb switching, so I got a cheap ($15ish?) usb switch (one downstream port (connected to a hub), two upstream ports, and a button to switch between them), and run a script on my desktop to send ddc commands to the monitor to switch inputs when it receives usb attach/detach notifications. No keyboard shortcuts, but one button next to my keyboard switches everything.

: I've since replaced the monitor, and found that the new one doesn't support input switching via ddc, at all. But it does switch if only one input is active, and I rarely use both computers at once, so I cope.