Double jungling is fun, but don't try it in solo queue.
Personally I want to run double jungle with a combo of
^^^ in the above singed gets the XP
^^^Either (but not both)get XP
Lee Sin/any of the above
^^lee sin gets XP
Jayce?ezreal/Graves in jungle with Nautilus/alistar/taric.
With one of these three being in a slo lane as well. 2 ADC? YES PLEASE (need a CC support so ganks can actually happen)
Solo lanes would have to have good sustain and manueverability. Vlad, Jayce, Ezreal, Graves, Urgot, Chogath to name a few...