Wait it out, Both manufacturers are not that far away from releasing their next gen high end cards.
Either go for those or at least wait for the price drops on older cards.
I don't recommend 2x 970's at all!
Always go for a the highest single card you can afford, And if you do go dual then once again always go highest cards so it will at least last you a few years.
Dual midrange never lasts better off paying a bit more upfront.
I am still running 2x780 cards from day 1 release, Have lasted a few years now and still no worthy card/s to upgrade to. Next gen 300 series or big Maxwell will be the true successor for those still on high end from a few years back. Current cards are just midrange even the 980 cards are the smaller die size...