Actually the impetus for a tri-monitor setup was the flight sim "Rise of Flight" (ROF). I have BF3 but actually prefer COD MW3.
The 3 monitor setup with a flying game like this is great! Rise of Flight is based on WWI planes and, though I'm truly a novice, it's a lot of fun flying it.
Flight sims and driving games benefit from triple monitor as much as FPS. You can see where you are turning into (and if a plane or car is already there), etc. Plus it's just prettier. But you already know this, haha.
People complain about bezels etc. but funny thing is how they don't complain about the A-pillars on their cars... same thing. (Some people also do not understand that triple monitor allows for a greater field of vision; they think a single 30" monitor gives them that. Doesn't matter how much you explain aspect ration and FOV to them, they just don't get it. Sigh.)
My impetus for going tri-monitor was more pedestrian: I wanted to lower the odds of getting backstabbed in TF2. I didn't get backstabbed that much in the first place and was a very good player even on single screen, but I became VERY difficult to sneak up on once I went triple monitor + Surround headset.
I also discovered that the Storm of the Century spell combination in Dragon Age Origins was more useful when you could go triple monitor and cast it farther away from yourself... so my mage wouldn't accidentally kill herself with it, lol.