New Road Bike Ideas

I am starting the process of investigation for a new road bike. I am a big
guy, 260 lbs, who puts in a lot of mileage. My two main road bikes are a
2002 Klein Quantum Race and a 2002 Cannondale CAAD 4. Both are built up
with Ultegra.

I had a severe spinal injury in the past, and have a long fusion, so I ride
with a tall stem and 26 mm tires for a more comfortable ride. I like my
bikes but both have a very similar ride and I am pretty beat up after a ride
of five or six hours. I love to climb but want to make sure that I don't
get into the "stupid light" category. In the quality/price trade-off I am
more on the quality side of the equation. I am looking for suggestions of
brands & models that you have had good experiences with. If you have any
ideas, I would love to hear them.