General travel and snapshot photography

I recommend the S100 because it has a larger sensor 1/1.8 compared to 1/2.5.  It as a f/2.0 lens which lets more light in and the Lumix lets less light in but has more zoom. 

larger sensor, fast action. good in natural light, great jpeg engine, a little wak on detail.  watch out for the low zoom, pocketable, shoots raw.  but you'll need a very steady hand to stablize camera from your movements,  manual controls but a tad cumbersome to use.

First, these two cameras are generally classified under two different categories.

Canon S100 is classified as a high end "posh" cam, hence the significantly higher cost than Panasonic ZS10.   Other examples of high end P&S cameras include Canon S90/S95, Panasonic Lumix DMC-LX3/LX5, and Olympus XZ-1 to name a few. 

Common to them are: 1) bigger sensors (1/1.6 or bigger versus 1/2.3);  2) faster lens (f/1.8 -f/2.0 - it allows for better performance in low light);  3) limited zoom, between 3x and 5X (ususally the limit corresponds to the speed of the lens, greater the zoom, greater the optical compromise for convenience sake);  4) Higher cost and better build quality

Panasonic Lumix DMC-ZS10 belong to a category called travel zoom, whereby it has a fairly compact body when the lens is retracted but it has more than 10x zoom.  They are usually between 12-16x zoom and most all contain smaller 1/2.33 sensors. 

Other examples of this type of camera include Nikon S9100/S8200, Canon SX230HS, Fujifilm FinePix 550 EXR and Sony Cyber-shot DSC-HX10V.  Having a longer zoom can be useful under certain circumstances; however, if IQ is paramount, S100 is a better choice.  Also, S100 does better in low light situations, although in reality,

only marginally better, not significantly so.    Even smaller new CMOS sensors tend to do better in low light than previous

gen. CCD sensors. For ultimate in IQ for P&S, if money is not an issue, I would recommend Canon Powershot GX1.

I just recently bought the Canon S100, after having used a Lumix DMC-LX5 for around 2 years.  I'm starting with that, because I'm partial to the Lumix camera by sheer virtue of being more used to a part of the Lumix line.  I haven't tried the ZS10, so sorry if I'll be comparing the S100 to an LX5; I just really have great respect for the Panasonic cameras.

I honestly feel that the slightly slower focus, and slightly more saturated color are disadvantages in using the S100.

Don't get me wrong, it takes beautiful pictures, and almost seems like it has built-in "filters", at times, if you want that kind of beauty.  

Also, it is truly "pocket-able" as many reviews say, it is small, thin and light enough to be truly portable. So if that's important to you (as it was for me), this is a big plus.

I just miss the image sharpness and wide-angle of my old Lumix (LX5).

Canon. Considering your planned uses - landscapes, buildings, family - I don't imagine you needing the faster shutter. The f/2 aperture and higher ISO settings will likely come in handy far more often, and a larger sensor with reasonably well-matched MP will give you better image quality. Also, I believe the Panny is all touchscreen, which can be annoying for someone trained in SLR photography. The Canon shoots in RAW format, too.

You can hack Canon to get extra functionality.

The best bang for the bucks ever. This camera win on all of your criteria, no questions asked. You're still here? Go get this baby!

Great quality, RAW shooting, Fast lens... enough?

S100 but throw in the kicker the s95 or s90 even may be all you need. Dave the extra $ for a beach day where you can rent stuff and take those pics!  But if you want the latest ad greatest s100 

I just ordered the ZS10 from Amazon  its way cheaper thn the s100 has long zoom,high shutter speed & less delay.

Canon Powershot as faster lens is better for portraits and you can shoot in raw so better image quality

Better zoom, higher mega pixle sensor...