Could use Some Advice on Graphics Card

Hello, Upfront I apologize if their is already a post over this topic, I just cant for the life of me find a forum with the same decision im looking at. Im currently building my first big build and I have am planning on eventually having three 1080p 24" monitors for gaming mostly and some multitasking.

Currently I have:
Motherboard: Asus P8z77 LK
Power Supply: corsair tx650 (i know itll probably be cutting it close with power doing a sli configeration)
Memory: Corsair Vengeance 8gb
CPU: Intel I5 3570k

My first question is your guys opinions on the gpu or gpu's I should go with. Im a fan of the galaxy and asus 600 series cards so that is mainly the area I am looking into.

My first choice was to eventually sli a pair of 660ti's 2gb. My worries were if the 2gb and smaller memory buss would be able to handle it fine.
I also looked at the 3gb versions of the 660 ti's, but their is a significant price jump right now since the 2gb are on sale right now.
Lastly i did look at the 670 2gb and 4gb cards. However, unless it was a huge difference I would prefer not to spend that much. Im a college student so im trying to save up and have been buying the whole build piece by piece.

I would greatly appreciate any opinions you guys have on this. Im kinda confused at this point honestly because it seems that every thread I read has a very different opinion.