Check out my rigs if you'd like. Personally, I don't like gaming on 3 screens, and I absolutely hate gaming in 3D lol. I've tried both a fair bit. I do however love the 120hz that 3d-ready screens have, and am quite happy with GTX 580s so far. I had 560 Ti SLI before, and definitely prefer a single 580.
If you wanted to get a cheaper card you could - the 560 Ti or 570 are great choices, but slightly less powerful.