First Road Bike - Some Options and Issues
Tires can make a significant different in terms of comfort, especially on uneven roads.  If you're comparing two different bikes, ask what is the largest tire that either one can handle.  

I used to have a road bike where some 25mm tires rubbed on the front derailleur clamp (a tire labelled "25mm" is not always 25mm wide). With that bike I didn't have a choice - 25mm or 23mm tires was all I could use.  Those narrow tires require high pressure and are uncomfortable.

Now I have a cyclocross bike that can use tires up to 40mm, and I'm currently running 35mm Schwalbe Kojak tires. It rolls as fast as any other road bike (I ride with a group, and coasting downhill behind other bikes, I can see that my bike isn't slower). But most of the impact and vibration from the road surface is absorbed by the tires.

There are some road bikes, such as the Specialized Diverge and the Norco Search, that work with tires up to 32mm (with fenders) or 35mm (without fenders).  These are sometimes called "gravel bikes", intended to be rideable on gravel roads.  Obviously they also work very well on paved roads.

You don't have to use wide tires -- but it's good to have the choice. You can try it out and see if you like it.

If you're comparing specs, you probably want the following, based on what you stated as your goals in your question:


greater tire clearance
longer chainstays (results in tire clearance)
greater vertical distance between bottom bracket and handlebars