Comfort is in the eye of the beholder. Comfort depends on the hills you climb and the kind of roads you traverse. Chromoly steel bikes are still made for a reason... they're not as stiff as an aluminum or carbon fiber frame. If you're not hitting any singletrack trails at high speeds, you don't need full suspension for a "leisurely" ride. Modern bikes have come a loonngg ways and there's sooo many options out there for frame geometry and handlebars and seats and etcetera. My best bet for you, since you seem kind of unknown to the cycling world, is to speak to a bike shop about how you want to ride, but don't let them try to sell you. Another way is to Google. I'm a newbie here on this forum, so I can't post links yet, but BikesDirect and PerformanceBike and BikeNashbar are awesome catalogs to window shop through. Handlebars and handlebar extensions and seats and padded shorts and shoes/pedals make the bike more than anything else. There's a thousand different variables that can make a bike "comfortable." Look at BikesDirect first and foremost if you have a budget... awesome deals there. You can also look at bikes at all those online catalogs and get an idea of what style that you want. Look at all the handlebars and seats and shorts and shoes/pedals too. You may want a new handlebar, and don't let front suspension sell you either if need be.
Comfort has many variables to each specific rider. I hope I helped, and sorry for the late response.