Sorry for the late reply!
Ah, I see. Skyrim doesnt really need 4gb either, but those 3 monitors will! Okay, so 4gb is a necessity.
As far as having one or 2 cards go, I would say it is always better to have more than one. Not only are you getting more performance but when more games are released with PhysX technology, an extra card is really going to pay off. I find my second card very useful at the minute, as I already play alot of PhysX enabled games. The second card will take some of the grunt away from the first card you see. But, as you say, if you go for 1 770 now, you can get another in the future!
I would definately suggest an EVGA card, as EVGA are the no.1 GPU manufacturer for Nvidia and work very closely with them. but if the 4gb EVGA card is too much, then I would suggest either Palit, MSI or Gigabyte. I dont really like Asus or Zotac as I have had cards from both and they have all been RMA'd in the past several times. =(