I recently got into a discussion on LinkedIn on how to let the Sitecore authors style their pages more easily, and it seems like folks out there are still a little confused on how to use parameter templates for your sublayouts.
I guess the first thing that everybody should know is that you don’t NEED to use parameter templates to make your authors make choices. If the choice is going to apply across the entire visualization of the page, that starts to sound like something that should be on the content item data template, not on the sublayout.
However, with DMS and personalization, we find ourselves building a lot more components into our solutions, which means the authors now need to be able to provide configurations at the sublayout level instead of the content item level. There could be three promo boxes on a page, for example, and we cannot apply a single configuration from the content item to all three. Parameter Templates allow us to provide the author with a sublayout configuration interface that is more familiar and straight-forward then providing key value pairs using the standard configuration fields that are available out of the box.
My colleague Nick Allen and I did a series on this a while ago, and Nick really did a deep dive into this with some great examples. Take a read: