We are considering a drastic overhaul of our 5+ year old site - UI, structure, content, SEO, backend, etc. We are not ecommerce, we generate leads for a high cost product.
We're aware of the obvious benefits: better customer service, stronger branding, less bandwidth, etc.
A case is being built to fund this project, so the question at hand: what resources are available that would help us estimate what specific changes would impact a variety of metrics (conversions, leads, etc). I am looking for general information, not industry specific.