Some of the most notable contrails were made by the Consolidated-Vultee (Convair to you younger guys) B-36's years ago in the 1950's. The Russians were absolutely s..t scared of this aircraft due to its high altitude capabilities.
Yes, but in our lattitudes they rarely get high enough to make them. At the poles, you would see them more I should think. When we used to go chasing Soviet Bears during the cold war, we used to see their contrails from miles away.