In all honesty I wouldn't post it in our fanfiction area. Many people suffer from the inability to read anything longer than a couple sentences.
If you want to post it on AO, I would suggest putting it in your AO journal. You will still be able to get feedback, and you will have a better chance of getting some constructive comments from people that actually read the episodes.
A better idea would be to post it on a website devoted to web-published fiction. One possible place is fanfiction.net (if your story is a fanfic based on something that already exists). Another is fictionpress.com (if your story is original fiction). At either of the two sites you'd get feedback from fellow writers.