I like the 2GB models myself for us multiboxers:

http://www.komplett.no/k/search.aspx?q=560ti%202gb

Anything in that list besides the 2WIN version is fine if you can afford the slight price increase from 1GB to 2GB. Technically, that
2WIN card in the list can support 3 monitors on its own but, I have a feeling you might run into issues with that special dual-GPU
card while multiboxing.