Make sure Wi-Fi is *actually* down (specifically the chip having been *powered down*, not just network down).
Try to see if it works without re-enabling Wi-Fi straight away.
Try to see if it works without dealing with Wi-Fi whatsoever.
Remember my warnings about timings and pain (specifically mind your timings during the wifi power teardown; and sleep more before tripping suspend).
. Refer to the KOReader scripts for details on all of the above.
Also, I don't quite remember how rtcwake works, but I would only use it to *setup* the alarm, not to actually trip the suspend. I'd handle that one myself (especially since you need to deal with the state-extended sysfs node, which is an ntx-special, so you *have* to do that yourself anyway).