I did a waiver interview in Los Angeles a couple of weeks ago.
I mostly brought the same files that I already sent plus tax records during the divorce year and anything else I could produce. My advice bring anything/everything you sent to them during the entire process. The IO that interviewed me did not have a copy of my intent to switch to a divorce waiver from a joint filing. So he didn't have a copy of my final divorce decree or any other the documents that I sent other than the ones I sent over two years ago even though I sent an RFE package two months prior.