being a wide screen gamer I will lend you my advice.
I started with 2 x GTX 570's and then switched to a GTX 590. the 570's were a few FPS fast, but created a lot of heat and noise. I like the 590 much better for the less heat and noise. after reading THG review of the GTX 690/680/670 and the HD 7970. I would go for the GTX 690. this will leave you with a possible quad SLi path should games get more GPU intense and you find yourself needing a little more GPU to game in widescreen
Guessing not a lot of people go down this route then?
I have mixed feelings on wide screen gaming. it is fun once it is running, but the path to get there is long. a lot of games don't support wide screen gaming natively and need modification thru a config file to work. additionally the on screen menus and hud is usually all jacked up. also switching from an extended desktop to Surround mode is a pain in the backside.
I got my 3 x 1920x1200 24" monitors on close-out for about $130 a piece, so I went for it. in hindsight I would go with a single 27-30" 2560x 1440/1600 monitor for gaming. you still need a beefy GPU to drive it though.
Silhoue has a good point, but you need to take it one step further and go with a Z77 MB that has 2 PCIE 3.0 slots and an IVY Bridge CPU. The GTX 680's & 690's will utilized the bandwidth that PCIE 3.0 provides