The only major difference i see is that the s300 has a 3x optical zoom to the s110's 2x. I LOVE my s300, but sometimes wish i'd opted for the s110 simply because it's noticeably smaller. If you haven't already Tony, go to a Best Buy or similar outfit and hold them both in hand. I put my buddy's s100 in one hand and my s300 in the other, and was amazed at the difference. The s300 is tiny, but the s110 is unfreakinbelievably small.

Either way, you won't go wrong. The s300 rocks.