I always was under the impression that the reason Superman wants to spend time as Clark Kent is that he honestly enjoys being Clark - he gets a kick out of it and uses it to relax. This view is reinforced by Maggin, who says that Clark Kent is Superman's equivalent of Einstein's violin playing.
This view says wonders about Superman's inherent humility that he doesn't mind being an average Joe, and of Superman's respect for the common man.
Superman is different as Clark Kent, but I wouldn't say Clark is a "disguise." People behave differently amongst their rowdy drinking buddies than they do amongst their Mother, but this does not mean a person is wearing a disguise or being a phony. Different characteristics that one possesses are emphasized at different times and in different situations.
I don't think Superman one day put on a pair of glasses and "invented" Clark Kent from start to finish. The Clark Kent persona probably developed gradually, not all at once. Superman's own humility and lack of subterfuge probably means that on occasion, people that are not aware that he has superpowers would take advantage of him, and his refusal to get into confrontational situations where he might use his powers to hurt someone would give him the label of "meek" or "mild." Labels have a funny way of becoming reality - drill it into a kid that he's a brat over and over, guess how he'll behave? Same principle here. Clark Kent's "absences" during crisis situations would be interpreted as cowardice, an ugly insult he can never dispel because he can never explain himself. Superman would quickly learn to cultivate this characteristic of being easily frightened and sickly, probably the only part of the Clark Kent persona that really IS just acting and not a character trait that Superman possesses, only shown in a different circumstance. This would make his disappearances in dangerous situations perfectly in character.
One continuing discussion is whether Superman's persona is a "real" person or "Clark Kent" is. I would say Superman is both at the same time - both possess the most important of his characteristics, honesty, decency, and incorruptibility. At the same time, if ONE of the two persons has to be judged as the more honest to his "true" personality, I would have to say Superman is the more "real." If our true selves are revealed by the choices that we make under pressure, and as Superman, he is ultra-confident, intelligent, resourceful and always with a plan, clear-minded and certain of his courses of action, fearless, and steadfastly refusing to compromise his convictions. In fiction, the "true" self is the "heroic" self - Superman may be Clark Kent too, but saying he is Clark Kent and the traits Clark Kent represents, exclusively, diminishes Superman's grandeur as a hero.
Sadly, most people wouldn't recognize Clark Kent to be Superman because they don't care. That's what's wrong with the World today - people don't care - they have a sterylized mind and only think of themselves. That's for the people.
Very astute observation, Brainiac 44. It goes to prove a different and bigger point - treat every man as if he was a Superman.
Superman loves Clark Kent, I think, because Superman revels in Clark's ability to be dismissed and ignored, his anonymity - he has such respect for common people that he finds value in this. Superman doesn't want to be one of the "beautiful people" of the world. He loves the average person, and (to him) the exoticism of averageness itself - too much for that.
Why does Superman always crack a smile and wink secretively to himself when Lois says something like "You're nice, Clark, but you'll never be Superman?" Because he has FUN being Clark, he gets as much enjoyment out of these little dichotomies and ironies of his existence, as much as we enjoy reading about them.
And for the record, the recent PETER PAN was a wonderful, fabulous movie.