Honestly the 780gtx has dropped so much in price there isnt a whole lot of difference $$$ wise. Nor is there a ton of difference performance wise. You'll be thrilled with the 770, and yeah I think you'll be set for a couple/3 years.
Its a hell of a time to buy a graphics card. AMD changed the game with its 280 and 290 and Nvidea had to cut prices to stay in the race. I think this competition will go on and right now even someone with $300 to $400 can buy a damn fine card.