My sotries are often really long but they contain a lot of Dialogue as Caylith has said. I find it a lot better then just large chunk of data, and where you can get to know the characters. (Roddy and Rita). Unfortunately, this makes the story look larger then it really is.
In my most recent installment (soon to be more then one) is a lot shorter then my other stories, but I will be writing more.
And after reading Dreygons post, my writing is like that. I get an idea and i write and write and write until its done, usually making a long epic.