The frustration for me with DC is that the characters don't get anywhere, they don't arrive at the end of their story and they usually get rebooted or retconned before that, so it's like the myth of Sisyphus. It's very frustrating for a long time reader.
Sure some characters marry, have kids and even die, but their story is really about fighting for big moral imperatives and they never arrive at a point where the job is done and there's a sense of accomplishment. Batman doesn't leave Gotham better off for all his efforts, Superman doesn't cure the world's ills, Wonder Woman doesn't achieve peace and understanding. Maybe the big goals can never be accomplished, but it would be nice to see these hard working heroes get a little ahead on what they started.
The characters I always think of that got to the end of their story are: James Robinson's Starman; Archie Goodwin and Walt Simonson's Manhunter; and Neil Gaiman's Sandman. Who else?
I suppose in what-if Elseworlds imaginary stories there might be a few others like All-Star Superman. But which other characters arrived at a satisfying conclusion to their story, from any of the DC books and imprints?