I have the Canon PowerShot S110 Digital ELPH. Its nice and itty bitty, and fits in my pocket very nicely. I've had it for 2.5 years now, and it has worked very well. I wanted something that I could just take with me and take pictures with. It only has a 2x optical zoom, and that has been the only thing I've occasionaly wanted more, but with more zoom it dosn't fit in my pocket...

I like the portability. It has the LiOn, and with a 128 meg CF card I can take about 120ish pictures per charge and card size at full resolution. If most of the pictures use the flash, then the battery dies at about 95ish pictures, but that is still alot of pictures if you thing about it. The battery charger is well desinged and travels well. No cord, just flip out the prongs, slide battery in, plug into wall.
The Canon software worked very well while it worked. On my desktop, the software decided to ignore my camera about three months ago. Windows regonizes that it is there, but the Canon software(the download software) refuses to reconize that it is attached. I havn't fiddled with it that much(read about 20 minutes) because I've just used my laptop instead.
It does have some manual settings that I played with when I first got it, but havn't bothered because I don't know what most of them do/havn't the need.
I don't know what the details on the cameras you have, but Canon has good optics in general and I've been very happy with my S110. One lacking feature has been a large zoom, but with 2x (optical, digital zoom dosn't count) it is passable. Taking pictures while hanging out with friends is fine.
Pictures I took at the Annapolis regional. They were 1600x1200, but I shrung them.
http://www.members.cox.net/weffrey//...anniphotos.htm
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Looked at the specs for the cameras you listed. I would stay away from the A70 because of its use of AA batteries. Friends with AA digi cams are forever changing them. The S200 looks just about excatly the same as mine, with some physical layout changes. The features apear to be equliviant.
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Wetzel