I've also got the suspend problem here, but i've got no NUC.
my harware is:
AS ROCK B85M-ITX
Intel i3 4130T
Crucial 4GB DDR3-1333 RAM
OS is Openelec 4 and Openelec 3.2.4
With both OS i got the same problem. If i choose "Suspend", the screen turns black and the "ON" led starts flashing for 2-3 times. Then the system boots up again.
If i choose "Shut Down" the system shuts down as expected.
I've also tried all the bios settings and workarounds mentioned here with no success. Some bios settings let Openelec freeze when selecting "Suspend"...
That said, i guess it's a haswell problem and no NUC specific problem, cause i don't own a NUC.
Hope we can get a solution, cause i really need suspend/wake on LAN feature.