Shadow really is an amazing game, and apart from ICO, there is nothing like it, at all. It has some horrid controls (in my opinion), but during a frantic dash to topple the 3rd colossus, I realised just how much emotion this game was causing me to feel, and from what, imprecise controls! It needs a remake on PS3 I think, just to keep it current for future gamers to play and appreciate.
One series that really works for watching another person play is the legend of zelda. Ocarina of Time, Twilight Princess, they should both be splendid games for you to play and your wife to watch. I myself remember watching someone else play ocarina of time, and it was quite entertaining.
(I see germania beat me to it

)