Can't go wrong with Canon
I bought a 3.2 MP S220 (i think) about three years ago, back when the price premium for 5+ MP cameras was much higher than today.
The feature set is OK, but the main consideration for me was size. I figured if it did not fit in my pocket, I would not take it with me. The S220 is one of the digital versions of the Elf series, which are tiny. As a result, I can ride with it in my front or back pocket with no problems.
Also, the camera has an exceptional build quality, with almost all metal parts. A bit heavy, but quite small. Good battery life, especially if you use the optical view finder instead of the digital one.
If you can still find them, the Canon Powershot series (A40, A80, etc.) are exceptional values. Only real drawbacks are the build quality (plastic) and AA batteries, instead of a rechargable version. Some people prefer standard AAs due to widespread availability, but they are generally heavier, and are wasteful if you don't swap them out with rechargeable ones.
I've also heard great things about the Minolta Dimage series.
As far as resolution: I can get excellent 8" x 10" prints with the 3.2 MP resolution. I print these at home on Canon paper using a Canon printer. Since this is the largest size I can do by myself, I've never tried anything bigger, which would likely illustrate the shortcomings of the 3.2 MP resolution (purple fringing and 'jaggies').
Are you really going to be blowing stuff up to 'poster size'? If so, the extra megapixels are probably worth it. Just be aware that prints this size get very expensive. If you will actually be producing smaller prints (like up to 8 x 10), go with a 4 MP version that is small and has the feature set you need.