We are looking at possibly doing a similar thing. On our local systems, we use
Nintex2007 for our workflow management, and I know that it has a built-in action
called " Create a site". You feed it details such as the parent site, the
template to use, etc... and it does all the heavy lifting for you. Couple this
with an infopath form to gather the required info and some approval steps, and
you've got a nifty solution that is quick, and more importantly, consistent.