If you can afford to pick up a few more cards before your trip, I would recommend it. Get whatever you think you need, then double it to be on the safe side. Some people like to take smaller pictures so they can fit more on the card, but if you take the smaller picture you lose the ability to do as much cropping. I.E. if you take a 4x6 picture size, can't really crop out the stranger and still print a 4x6 where as if you were shooting an 8x10 pretty good chance you can crop em out and still print a good 4x6. I would recommend carrying a few smaller cards instead of one big card. Big cards do work good when you are shooting very very hi res/RAW pictures at high speed. However, as PP's have said, if something happens to that one card, all your pictures are lost. If you have a few smaller ones you only lose a portion of them. Backing them up to another source as soon as possible is also recommended.
For a 6MB P&S, 2-4 GB should be enough for the trip. I would get either 1 or 2 GB cards.
For a 6MB P&S, 2-4 GB should be enough for the trip. I would get either 1 or 2 GB cards.