Right, Wi-Fi will only go off once your Nexus 7 is in deep sleep.
To check whether your Nexus 7 is going into deep sleep install
CPU Spy from the Play store. There are many reasons why your Nexus 7 doesn't go into deep sleep but with this you can find out whether it is or not.
Because my N7 isn't my primary device (my N4 is), I have Wi-Fi set to go off when the screen is off. With this set, my N7 on but asleep in 13 hours of dormancy my N7 only used 4% battery which isn't bad considering what other have posted in other threads...
Sent from my 16GB Nexus 4 using Tapatalk 2