How to choose between a race bike like a Madone and a classics bike like a Domane I ride regularly for exercise in New York City but do not race. I currently ride on a steel frame that handles the rough roads easily. I want to buy a carbon bike and am torn between a "classics" bike like a Domane or a Roubaix and a race bike. My rides are usually around 2-3 hours so comfort is nice but not essential. I appreciate quickness in traffic and am comfortable with a race bike geometry but am worried about durability. Any advice on how to think about these trade offs?
I think you answered your own question when you stated "I don't race."  I know many in our club who enjoy the Roubaix.  I personally prefer riding my steel Soma ES over my carbon race bike for most things, including fast club rides.  Don't get me wrong, a twitchy race bike is great in a crit, but the other non-race bikes have had their design optimized for non-race road riding.  It is too easy to get up caught up in all the bike porn the industry pushes.  A solid, well sorted, well maintained, properly fitted road bike of any class and age can be a great riding tool.

In the end this is just all opinion, but I would be careful not to get caught up in the industry's push for "race" performance, which only serves a small minority of road riders.