The following sentence utilizing the Compound Superlative structure would be translated as -
St. Petersburg is one of the most beautiful cities of the world.
Санкт-Петербуг - один из самых красивых городов мира.
How would this sentence which utilizes the Simple Superlative be translated? Would it be translated as - St. Petersburg is one of the highly beautiful cities of the world?
Санкт-Петербуг - один из красивейших городов мира.
My grammar book lists these examples
Билл Гейтс - самый богатый человек в мире.
Bill Gates is the richest man in the world.
Он богатейший человек.
He is an extremely rich man.
Also is simple superlative often used in speech or is its use more literary?