I'm using 'Classic DCU' as a blanket term for DC's entire history before Flashpoint because lets face it, the elimination of the Multiverse and a few reboots aside, the DCU was pretty much the same animal up until the start of the New 52.
The truth is that I'm already seeing a fair bit of New 52 influence in the movies. Superman's suit for instance is an awful lot like the New 52 suit (though I dunno if it was influenced by that suit specifically, or if WB and DC simultaneously developed modernized Superman suits for both versions without the red shorts). And one can argue that the more aggressive Superman at odds with the authorities and the military is a lot closer to the New 52 version than the 'Boy Scout' of previous eras (then again, the New 52 version does channel the original Siegal/Shuster stories in that regard).
Batman's suit is said to be based on Miller's design from DKR...but to me, the bat-symbol and shorter ears aside, it can easily pass for the New 52 Batman suit as well (which again, itself is sorta a cross between the Year One suit and the Nolanverse Batsuit IMO).
The tentative inclusion of Cyborg in the Justice League, rather than Martian Manhunter, also reflects the New 52, as do the rumors of Jason Momoa playing Aquaman as an 'anti-hero'.
On the other hand, Superman is portrayed as being in his early-to-mid thirties and Batman is even older. They are certainly significantly older than their New 52 counterparts and a lot closer to the ages they've been traditionally portrayed as. So there's not as much emphasis on the DCCU being a 'young' universe, which reflects the Classic DCU. Martha Kent being alive and a constant source of guidance and emotional support for Clark, as well as Lois being aware of Clark's identity and being his confidante, also channel the Post-Crisis Superman mythos far more than the New 52. The idea of Clark traveling the world before becoming Superman is also from various Post-Crisis Superman stories rather than the New 52 (which basically has him moving to Metropolis fresh out of college and becoming Superman).
Personally, I think a 'best of both worlds' scenario, leaning more towards the Classic DCU, is the best bet. In terms of costumes, and other aesthetics, and perhaps elements such as the world's/government's perception of and reaction to superheroes, its probably best to go with the New 52. But in terms of characters' mythos and characterizations, I'd prefer they mine the Classic DCU (which is after all, the source of the New 52 as well).
The New 52 is a modern reinvention of the DCU...just like the DCCU is aiming to be. Instead of adapting another adaptation, why not just draw from the source, while taking some pointers from the new adaptation.