I don't understand why people make table shots sound so complicated. I just keep to 1/60 F5.6 at ISO800, direct SB800 with the WA adaptor. As long as you keep you seated and standing guests more or less the same number (so that most of your frame is filled by subjects at the same distance), it is highly unlikely to go wrong. I just dial in +0.5 of flash compensation whenever there's too much of the white table showing.
As for ambient light, sure you can get your background slighly brighter by bringing your shutter speed down further, but at what expense? Unless you gel your flash head to the similar temp as the ambient lighting, the people will be subject to uneven coloration (due to different temps in flash and ambient).
Never had a use for omnibounce and cards, they just use up more flash power and don't make a difference. I like to take two shots quickly so as to prevent blinkers. As long as you use a bit of common sense with your flash compensation, it's very easy to get properly exposed photos for every single table shot.