My bartop has the PC sitting below it. It works well, but I don't think it's really worth it. Once you have the PC configured, there's no advantage. That's why all my bartop's have an area for a PC now.
If you really need an easy way to adjust the PC fairly often, try either a KVM switch or some VNC software. I like the VNC stuff personally, as you can use a laptop and just plug in. Try TightVNC, it's easy to get running.