Great point about tires... huge difference between certain types of road tires. And you can make them all ride like hell if you're not that heavy yet pump them to max pressure in erroneous pursuit of optimal rolling resistance and handling.

After tires, then it depends on your conditions. Most people ride fairly good roads and wouldn't notice the difference between a S5 and a Roubaix. Most people don't need the thick poofy gel tape that Specialized puts standard on their endurance road bikes, and you never see on pro bikes outside of the cobblestone classics. Most people don't spend any time on gravel washboard roads.

But if you do ride in those poor conditions, the tires, frame material, frame design and even bar tape can matter a lot.