Canon is pretty solid. You pretty much pick a price or form-factor and go from there.
The A series (e.g. A3300) is the low-end but still pretty competent. Some designs have better zoom lenses. Not as small or well-built as the ELPH line. Can fit in a jeans pocket. $100-$180.
The ELPH series (formerly SD series) (e.g. ELPH 300, SD1400) is the most compact while still being relatively affordable. Metal bodies, nice design. Easy to fit in a jeans pocket. $180-$300.
The SX series is the biggest physically; they tend to have large zoom lenses while still being relatively affordable. Most of these won't fit in anything but a large jacket pocket. $230-$430.
The S series (S95, new S100) is pretty small (though not as small as most ELPHs -- comparable with most of the A series) while packing in a better lens and sensor, along with other features. $400+
The G series (G12) is basically a bigger S series with more knobs/controls and a bigger zoom lens, but not as big physically as the SX series. $450+
I have owned a couple of SD line cameras over the years. They have treated me well until my wife dropped them and they started acting up. Actually they can still take pictures just fine, but the controls (buttons and zoom sliders) are now hard to use and sometimes unresponsive. But they are great in terms of being easily pocketable while also being fairly affordable. If I pay $200 for a camera that lasts 2-3 years then I don't see it as a big deal. If I were buying one for myself then I would go for the S95 or G12. But then I have big DSLR's for serious photography, so I have gone with the SDs for their price and tiny size.
The only thing that Canon doesn't have going for them is a folded-lens design (a lens that doesn't protrude from the front of the camera) and, to go along with it, a "Tough" design (the Powershot D10 is pretty cheesy compared with the "Tough" cameras from other brands IMO). In this vein, on the low end ($150 or less) go with the Olympus TG-310 or on the high end go with the Panasonic DMC-TS3 ($300+). Both are resistant to water, shock (drops), and dust. After having various issues with dropped/damaged Canon SDxxx's over the years, I bought the Olympus for my wife about a month ago. The Olympus is great for the price, but I'd prefer the Panasonic for its greater toughness and overall quality (e.g. 30 feet of water vs. 10 feet on the Olympus). I also generally like Panasonic P&S cameras in general, right behind Canons.