Vibrations from the road is not something I've ever considered since it has not been a problem in any of the bikes that I've had.
My primary considerations when considering a bike would be: * Price * Durability * Cargo support (like basket and rear hub)
A perfect example of this is the Cannondale CAD3. It had a massive downtube and huge (straight) seat stays as well. It was extraordinarily stiff and terribly unpleasant to ride, for most. Cannondale improved that to some degree by using S-shaped seat stays on the CAAD4 making the frame a less-efficient conductor of vibrations.
Modern aluminum bikes use hydroformed tubes with optimized shapes and shouldn't really have these problems. Unless you're talking about something with an aluminum fork. That's just a cheap bike. Aluminum forks are terrible.
https://www.youtube.com/watch?v=4WpGsJKVhZY
Thank you. I kinda always wondered how bike frames were made. This is really cool.
Source : I've shortened a lot of forks.
As to what's rare, hell if I know. Aluminum forks are fairly common on low to mid-tier bikes and the cheap ones tend to suck.
I biked 20km back and forth to school daily for six years, and 80km road trips are not something out of the ordinary. I don't think I've ever noticed anything about vibration. But that is in the countryside of the Netherlands, with flat terrain and good roads.
The worst thing I ever had was stiff knees for a week after, from inflammations caused by biking in too high a gear for too long.
Try to do a blind test on yourself sometime, with the same tires and tire pressures.
I don't notice "vibration" at any distance unless its nasty chip seal at which point nothing will save you short of a mountain bike.