Shadow of the Colossus doesn't impress you? I was hooked from the beginning, but I've NEVER in a video game, before or since, experienced something quite like the awe I felt when I had to go up against that skyscraper-tall giant that I swear took like 45 minutes to finally get to the top of.
Ico is entirely different, though. A lot more laid-back, actually, and pretty; it's fun just to look around and admire all the architecture and such.