I agree with Steve, a monopod is useful for supporting a very heavy lens, but doesn't add enough over hand holding for me, especially if I have I.S. lenses. A small tripod is very useful -- I just got the Gorillapod SLR Zoom, which will hold most anything I put on it, within reason. And it fits inside my small courier bag.
By the way, for a big trip I would bring both the SLR kit and the p+s camera. There are plenty of times I want to have a camera with me at dinner, etc., but not the SLR.