I am conisdering the same units, along with some others.

The Optio is nice and has nice features, but image quality is relatively poor. The SD110 takes nicer pics, and is also very nicely sized.

Take a look at the Olympus Stylus 300. Weather proof, slightly different dimensions but still tiny. Takes nice pictures, but the memory is XD card, and since I have SD cards I tend to be leaning towards the others. If you have no memory card investment to protect, then it might not matter.