Crossing over with Tearjerker and Moment of Awesome, Superman's "last" words are asking for assurance that Metropolis is safe. Only then does he die. At the end, it was the determination to end the threat to others' lives that was keeping him alive in the arc's final issue.
During the "Funeral For a Friend" storyline in the early 90's, Ma and Pa Kent are unable to attend Superman's funeral in Metropolis, so to say goodbye to their son, they bury a box containing items from his childhood (including a blanket and a teddy bear) in the crater made by his spaceship.
During A World Without Superman, Batman intercepts a terrorist who wanted to blow up the funeral, and stated that in honor of his fallen friend, he was playing it by Superman's rules.
The Man of Steel AKA John Henry Irons is the only replacement who admits upfront he is NOT Superman; Rather, Superman saved his life and when he found out his inventions were being sold to gangsters, he created the Steel armor to fight crime in Superman's honor. Lois Lane notes later that, even though he's not Superman, he at least has plenty of Superman's spirit in him.
John saves a construction worker in what would have been a Heroic Sacrifice had Superman not been present. Supes tells John that it's easy for Superman to risk his own life because he has superpowers, but for someone without them, it's more impressive. When John tells Superman he owes Supes his life, Superman replies, "Then make it count for something!" Later, when Steel reveals he's John, Superman muses that John really did take his advice seriously.
In "Funeral For a Friend" the death of Superman was such a huge loss that it was basically treated like a Crisis Crossover. Special props to a moment from Batman during the nightmarish lead up to the Knightfall event, where a morbidly depressed Bruce Wayne wallows in despair in the cave, and it's revealed that he's still wearing one of the JLA's Superman-Shield black armbands, reminding the reader just how miserable and hopeless Bruce's world is right now. Because he can't even call up Clark to help him, either with his problems or with emotional support, just when he most needed it. Awww...
The entire point of "Funeral For a Friend" was to show how much Superman was loved by the entire planet and a great tribute to the character.
Just the title, "Funeral For A Friend." To the world, he may be Superman, Man of Steel... but to the JLA, he's nothing more or less than a friend.
By the end of The Death of Superman, Lois Lane is an emotional wreck. She's gone through the trauma of Clark dying in her arms, has had to deal with his four would-be heirs, and even when the real Superman initially comes back she won't allow herself to believe him despite some very compelling (and very personal) evidence. After Supes takes down the Big Bad with a little help from his friends, we cut to Lois in her apartment, lying in bed fully clothed in the middle of the afternoon, possibly hung over. She hears a tapping on her window and assumes it's a bird, a call back to a scene much earlier in the arc. She flings open the drapes to reveal a great big "S." The next scene is a full-page panel of Lois and Superman kissing in midair. Text reads, "There isn't a doubt in her mind. She's in his arms... faster than a speeding bullet."
The issue after that shows Superman rescuing a young boy and girl (presumably brother and sister) from a disused Civil Defense shelter where they've been trapped since the battle with Doomsday, a couple of months at least. The kids have been living on the food and water supplies they found - they're malnourished and dehydrated, but they're alive. The little girl tells Big Blue that she kept reassuring her brother that no matter how long it took, Superman would eventually come and get them - he wouldn't let them die. Superman replies that he would rather die himself. And we believe him, because he did.
In a scene after Superman comes back, Jimmy Olsen is caught at the front of a giant crowd looking at the returned hero and wishes he had his signal watch with him so he could get his friend's attention. Superman then reveals he heard; he scoops Jimmy off his feet and tells him he's happy to see him again too.