Man, either your phone has issues or you're doing something wrong. I work in a place that is without signal 80-90% of the time (even on my Moto Droid I was without signal that much so it's not my GNex reception that's the problem) and with moderate use I can still make it through an 8 hour work day and the hour of driving to and from work. So I can easily get 9+ hours. With Juice Defender turning mobile data off and only turning it back on once an hour to sync for 10 minutes, I could get 15 hours or so.
Now I have NFC tags at work and home and have my phone set to turn off mobile data when I scan the one at work, turn on mobile data when I leave, and turn on wifi when I get home. Doing that with moderate usage I still have 40-50% battery at night after being off the charger for 15-16 hours.
I also have the extended battery so I always have my stock battery as a backup if I need it and I'm rooted and running a custom kernel and ROM