I had a DW in the same city as milkgal, VEGAS!. My biggest fear was just making sure that we didn't forget anything at home that we needed. That didn't happen. I'm a list maker so I had a list for everything.
We were able to go out to Vegas a couple of times before our wedding to confirm everything and see venues so that helped with any nervousness.
I think that having people that are well organized and communicate really well helps, too. Our coordinator at our reception venue, our photographer and our cake baker were amazing!