Our experience was generally similar to Jay's. I have a couple of comments that relate to what I have cut out of Jay's post below:
1) I agree with Jay that you can be TOO organized. Have your documents in order. Have other evidence organized, where you can retrieve it if necessary. But there is no need to bring big binds, photo albums, etc. As posted before, a lot of this stuff is never asked for and if it is, big binders and albums will not fit through the window opening.
2) I continue to believe that it is preferable for both beneficiary and petitioner to attend the interview, if at all possible. More of "dress code" later.
3) As for arriving early at the embassy....All appointments are scheduled at 7:00. From what I could discern, arriving early allows you to get at the front of line 3. This allows you to enter the embassy more quickly. It also allows you to have your documents reviewed by embassy personnel more quickly (as Jay says, the first review is simply a review of your documents...making sure you have everything, making sure they are in order....the embassy employee also highlights certain "key" piece of information on the various documents you provide).
However, I saw NO correlation betwen the order in which you had your documents reviewed and the order in which you were actually interviewed by the CO. We were interviewed ahead of some folks that had been ahead of us in line...and I also recall at least one person who was interviewed before us, but who had been behind us in the initial line. Thus, our experience was contrary to Jay's.
4) Jay and his fiancee were lucky. Our interview did not commence until after 11:00. Others on this board have not been interviewed until after 12:00. So, be prepared to be there for several hours.
5) As for dress at the interview.....I personally am glad I did not wear a suit. The seats are the embassy are not very comfortable and you are basically outside. You could be sitting around for several hours. I wore jeans and a Columbia (note the spelling) shirt. My wife looked nicer....with a skirt and nice blouse. Don't forget that the embassy folks already know all about you.....occupation, income, assets (in some cases)....so I'm not sure that dress is really going to make much difference....unless the beneficiary carries it to an extreme (e.g., looks like she just came from a job at the local casa). Honestly, the only guys I saw in suits were Colombianos....and I can remember at least one who was unsuccessful....from what my wife heard him say.
I do agree with Jay about mannerisms, composure, and how you carry yourself. I have no idea if anyone in the embassy was monitoring the cameras....or if the COs were watching any of the folks as they waited. However, I do know that my wife and I positioned ourselves so that we were directly facing the interviewers windows (we were in direct cite of the guy who eventually interviewed my wife). We held hands, chatted on occasion, and, I believe, generally looked confident and relaxed. We joked around and laughed some. When she was called to the window, I followed behind her and then stood right behind her with a slight smile on my face.
The result? As I've posted before....my wife was approved in seconds. The interviewer had no questions for her at all. He asked for no additional evidence (beyond the photos, copies of reservations, and e-mails we had submitted with our I-129F).
Mike
QUOTE(Jay1234 @ May 22 2007, 03:45 PM)

General thoughts- Preparation is everything. I think that having all the documentation in order is key to success in this process. It ensures that you are not scrutinized and it also makes you feel more confident at the interview. Skip clips, binders, etc. You don't need them.
I also believe that it pays to have both persons attend the interview and to dress well. Not strictly neccesary, but I wore a suit. Probably about 20% of the people there did the same.
It is important to go early because I believe it influences your success in receiving the visa the next day (more on this later).
You line up near the higher numbered windows (20-32, I think) and the same employee who checked our appointment letter then handed out the folders (you have to sign on a roster that you recieved it, which I think is how they determine roughly in what order you are interviewed by the consular officer).
We were then sent over to a seated area immediately to the left of the windows to assemble the packet. After about 10 minutes, we were called to one of the windows.... My impression was that this was just an intitial check of the packet.
Like I said, I decided to attend, wear a suit, Catherine dressed conservatively, and we were being (naturally) affectionate with each other. I do not know if the consular official was monitoring any of the cameras (though I know somebody was, one of the couples on the way out took a picture of the embassy, and were quickly confronted by security. They had to earase the photos before they were sent on their way), or if there body language was wrong at the interview, or if it had to do with something else altogether. But because there may be observation going on, I would suggest making sure that any jitters or nerves do not launch a fight on the day of the interview.