For checking NS renders, I dont see how automating would really help, as you have have a human there to make a subjective decision. Surely automating it would take longer than the QA dept trawling thru' a few web screens (depending on the size of the app).

If your html engine is centralised (ie all the html code gen passes thru' the one spot), I would be inclinded to take a sample of perhaps 10 different web pages (or a significant sample) and verify those.

You can then present your UAT doc to mgmt. If mgmt are particularly anal about these things, I reckon including a disclaimer such as "All HTML is produced via a centralised HTML engine."

If you have a large site, you'll be getting into the land diminishing returns which is obviously just not efficient.

I personally think you would be after a process template, rather than automating a point and click solution. With the process template, you'd have a bit of doco that has all the tests you require, all you have to do is perform the tests on "the next platform" and put the results in your document (word templates work well for me).