Here's my take on Brooks saddles:

Brooks B17 - Your touring bike has somewhat of a relax frame geometry. You ride mostly on the hoods and occasionally on the drops.

Brooks B17 Special (copper rivets) - Same as above, but you live or will be riding in areas exposed to lots of ocean breeze. Copper will not rust! For example, many people riding the Panamerican Hwy report their regular B17 saddles looking pretty rusty at the end of their tours. Furthermore, copper rivets are hammered really flat. It is true that you experience less snagging of your shorts on these. So, the copper rivets are not just "cosmetics." The aesthetics is definitely a big bonus.

Brooks Team Pro - Narrower than Brooks B17. Use this saddle if your bike has more of a race geometry. You spend a considerable amount of time on the drops.

Brooks Sprung Saddles (Flyer, B66, B67) - Your bike is set up to ride in a very upright position to activate effectively the spring mechanism. These are great on urban bikes, but some tourists with flat or butterfly bars like them. If your bike is set up with drop bars, sprung saddles might not be the best choice.