Note that one of the main criticisms of the G10 - high noise at higher ISO - is accurate. I had a G10 and decided I should never go above ISO 200. The noise, even for just viewing on a computer, was severe. This is a limiting factor in my book.
I haven't done too much with the S90 yet, but initial impressions are quite favorable. Supposedly the batteries don't last as long as the G10/11, but they are a lot lighter so you can pack a couple more. I just ordered a 3rd party battery from amazon for $6, plus free shipping since I ordered something else. From what I've read these work as well as the $40 Canon battery, but I've not verified that myself yet.
http://www.amazon.com/gp/product/B001FA ... ss_product
There is hardly a perfect point and shoot camera out there. Realistically, they all stink at high ISO pictures, some just stink a bit less than others.
The Canon S90 is probably the best choice for hand-held low light, as it has a faster max. aperture than the G11, and the same sensor. The LX3 is a little noiser, but it has a faster aperture than either on the telephoto end (though pretty limited in focal length). The G10 is noisier than those three, but has the best resolution if you leave it around base ISO.
The G10 would be best for image quality if you don't mind taking a small tripod for those sunrise/sunset shots. The S90 is the simplest to use, the smallest, and does well hand-held. The LX3 has more options, but is a bit bigger, slightly noisier, and limited in terms of focal range (though it does sport the only 24mm lens). Finally, I don't much see the appeal of the G11, besides the swivel screen (don't count on the viewfinder too much, they are basically worthless for accurate framing on P&S cameras, and you can't see the settings in them to boot).
But at least you are looking at some of the best the point and shoot world has to offer. I'd forget the Nikon P6000, its' image quality is pretty bad compared to these other candidates (very poor noise reduction artifacting). That coming from a Nikon DSLR shooter!
I agree with the others; battery life will be a problem on a P&S, it's a fact of life. I'd count on bringing extra batteries, and definitely keep them in an inner jacket pocket if you are in cold weather. The S90's compact size puts it at a battery capacity disadvantage.
Personally, I'd take the G10, keep it at or near base ISO, use a small tripod or beanbag if necessary for support, and enjoy the most detailed RAW files of any P&S camera when you get back. You can fix a lot of stuff in post-processing, but you can't fix detail/resolution that wasn't captured in the first place.
BTW the new noise reduction/sharpening algorithms in Adobe Camera Raw 6 (found in Photoshop CS5 and Lightroom 3) vastly improve the picture quality of P&S raw files. I have a bunch from my old Fuji E900 that look much more detailed and less noisy than ever before thanks to this new software. There is a public beta of Lightroom still available if you would like to try it out.