There are lot of standard options, which should be put into QEMU command line.
There are also some common knowledge bases regarding what type of virtual hardware is better suited to particular OS.

So, we need some wizard-like script which would create [vm script]. 
Current idea is to use some text-based fullscreen UI like dialog program to make it possible to use this creator on servers. Even if we take care of make machines easily transferrable from host to host using usial file operations, virtual machines are quite big and it can be feasable to setup them locally.