I had my interview today at 12 pm. I'd emailed beforehand to see if my husband and children could attend with me and they said this was fine . I had to email their names and relationship to me and was told to being their ID.
There was no queue outside so I went to the help desk and the lady checked our names were on the list and sent us to security. We were immediately approached by security who insisted relatives are not normally allowed inside and that the visa side was not the normal entrance for American citizens. I explained that I emailed and they went and checked with the help desk lady who showed their names (even though they were on his list). They seemed ok then and we went into security and had no issues.
Went into the embassy and received my number and then I was told to sit and wait. Took around 40 minutes to be called to the first window. It was a super nice lady who chatted to me and asked questions about Blackpool. She then asked for each of the documents and copies and checked them over. She looked at the I-864 and the sponsor and asked a few questions such as who the sponsor was. My son randomly appeared and she commented on how handsome he was and asked his age and about his personality. She asked when we intended to travel and I said ideally thanksgiving to which she replied "you'll have your passport back by then". She sent me to pay and told me to wait for my interview.
This was the long winded part. It was a couple of hours wait which made us anxious and they called the numbers in random orders. Finally I was called and when I arrived at the window I made an oath swearing to tell the truth. She asked how long we had been married, if I'd lived elsewhere,confirmed we had two children, mine and my husbands jobs and what we wanted to do in America. She asked about our sponsor and I confirmed that was also where we were staying. Then she said "congratulations, I'm going to approve your visa". She said it'd be about two weeks before it arrives.
So we were in the about 3.5 hours but it was worth it. There seemed to be some tricky conversations going on in the other booths and many people's interviews were a lot longer than mine.
I would definitely take snacks as there is only a water fountain in there (they have vending machines in the American side!). It was also pretty warm in there.
updated on October 31, 2016)