This is a very broad question which can't be covered in a single post.
My first suggestion is getting to know everything about each model.
Start by going to http://www.cisco.com/en/US/products/hw/switches/index.html
and click on each product family.
Second suggestion is giving your Cisco Sales rep a call, he will come onsite and show you how you can maximize your network environment and what product matches your criteria better.