In the present day fast-forward culture, everything should happen at jet speed. People do businesses across continents and Airplanes are a very convenient way to travel. But many people are not delighted to travel above 35,000 feet up in the air.
Every airplane has a certified maximum altitude. The highest certified altitude of an airliner was Concorde's 60,000 feet. Many of the corporate jets can fly at 51,000 feet.
Regular passenger international flights fly between 35000 to 42000 feet. That is considered as optimum height. "Each individual aircraft has an optimum altitude (for minimum cost or minimum fuel burn) which will be based on its individual weight," explains Peter Terry, a commercial airline pilot of 30 years.
It is an interesting fact, why do planes should go so high. One of the main reasons is, the air gets thinner with every foot of altitude. This helps the planes to travel more easily and move faster and of course results in burning less fuel and ultimately saving money.
Yes ... It is higher the better.
One more advantage of flying high also means that aircraft can avoid other airborne traffic, such as low flying aircraft and birds. So flying higher is safer.
There is less friction at higher altitudes, less friction, and higher airspeed causes engines to burn less fuel, therefore, it improves fuel efficiency allowing the airplane to travel further.