I started off at yakjujp 4.0.2 and flashed a yakju (stock US version) 4.0.2.
Google is only updating yakju or takju, anything else has to wait for the carrier or Samsung to roll out updates - yeah, right.
Within 2 or 3 minutes of my yakju burn it updated to 4.0.4 over the air - almost instant validation.
It took another 5 or 6 hours before it offered me 4.1.1 over the air without any further move on my part.
The initial burn that you do is the only one that wipes your data or apps, the others keep things across the update, so you can use the 5 or 6 hours to install stuff and play.
So now I am 100% stock US version, on the OTA mainline, and because this will mean I will get all of Google's updates OTA as soon as they're published with no flashing then I intend to stay there for a while, in this state I see no need to chase custom ROMS, there arent any at this level yet anyway, there isnt anything more up to date than a yakju Galaxy Nexus.
There are hard ways and easy ways to do that initial burn - I kept finding something never quite working with the hard ways. So I ended up with ths thread and the Galaxy Nexus Toolkit:
The beauty of this is that you dont have to follow pages of instructions, its almost "one click".
Obviously when rooting & reflashing your phone you should not avoid learning about the process and whats going on, doing something wrong will make your pulse race if not your phone brick, so the time spent is well worth it.
It is very possible that I now think this Toolkit is easy because of all that I learned trying the hard ways - sorry, I cant really tell any more :-) But that tool is a godsend.
The only tricky thing is getting the USB drivers installed - there are lots of instructions, but what they forget to say is that there is a 2-step process so here's a hint: you need device drivers like any new device does that Windows does not already know about, thats basic, and thats the first step, that gets the phone talking across USB. Then at the appropriate point you'll boot your phone into recovery mode while connected - and at that point you need to see Windows react by installing its debug drivers. I think every instruction I ever read just said "install debug drivers" as if we already knew about the 2 steps.
Once this is done then the Toolkit shows a huge menu of things and you just select "1" and go, or "3" and go, it does everything.
The USB drivers are supplied in the toolkit, too.