A couple more:
1. Be sure and spell out the rules in advance. If you're going to add a 20% tip to a restaurant bill and split everything evenly (the only want to make it work in my opinion if you're doing this at a restaurant) make sure everybody knows right up front they're paying an equal share whether they order a salad or caviar.
2. ALWAYS have a bottle of Champagne at the table. Not only is it a great way to kick things off and prime the palate for the tasting to come it's a great palate cleanser while tasting.