Yup, endurance bikes. The Cannondale Synapse is another good 'un. I think Fabian Cancellara finished his pro career Tour of Flanders ride on a Trek Domane, a little more relaxed bike than his earlier monument race wins (Specialized Tarmac, I think).
That category would be my choice for my next drop bar bike, mostly due to old and new injuries -- old neck and back, more recent shoulder and neck injuries. And ortho docs say there's age related joint deterioration on top of the injuries. Gotta be realistic at 61.
My road bike is an '89 Centurion Ironman, which is slightly relaxed compared with other bikes of that era -- crit and short stage race bikes that ended in sprints. It was developed for the early long time trial stage of the Ironman triathlon competitions. The original 130mm stem was too long and stretched out for my comfort. I switched to a 90mm stem and made other adjustments to make it a bit more comfortable but still fun to ride. And the steel frame and fork have enough give to be tolerable on rough pavement, as long as I keep the tire pressure reasonable and my arms and core are fit enough. But I can handle only 20-30 miles continuous riding before I need a break to stretch. So I've had to skip the longer semi-fast club rides the past year.
My favorite bike for longer more casual rides is a '92 Univega Via Carisma, with a longer wheelbase, more flexible fork, etc., all suitable for long rides and some gravel. But it's a little heavy, upright even with albatross bars at saddle height, and takes a lot of effort to push faster than around 14 mph.
I know from the one high end carbon fiber bike I've ridden -- a Specialized Tarmac -- that a good bike can be stiff and responsive but also ergonomically comfortable and not necessarily harsh. And lightweight enough to make a difference on climbs. But to be realistic an endurance bike would suit me better than the road race geometry of the Tarmac and similar bikes.