Cannondale builds great, USA made aluminum bikes. If you are going to buy an aluminum bike, don't even consider anything but a Cannondale. I'm a lot older than you, and I rode Cannondales exclusively till last year when I got my custom Co-Motion. You cannot get a better bike for the price.
I modified one of my Cannondales, a CAAD 3 frame, for touring and put 700/28 Conti Top Touring tires on it. These are big tires. They fit fine, but there wasn't room left inside the fork for the computer wire, so it had to be re-routed. The big tires do make a lot of difference in the ride.