I've always tried to get the best possible motherboard available at the time, and then just update the CPU and memory once or twice instead of getting new everything every couple of years. I was still using an old LGA775 Maximus Formula mobo I bought in 2007 before switching to LGA2011 earlier this year.
Anyway, Z77/LGA1155 is propably more than enough for you if you don't do video editing or rendering. X79/LGA2011 is more of a workhorse server platform in a disguise. The leap in cost between Z77 and X79 can't be justified by any rational means, but if you want the absolute fastest you can get, then go for X79. It's definately a good platform if you plan to use several graphics cards (thanks to 40 PCIE lanes) and the possibility to have up to 128GB of RAM for extra heavy apps.
A quad core 3820 is waste of money for X79 though in my opinion. Now that Ivy bridges are out, they don't fall too much, if at all, behind a 3820 in performance, and can be overlocked a lot more if you get a fully unlocked model (which 3820 isn't) like 3570K. If you do go for X79, I wouldn't get anything less than 3930K, not that you have much choice until Ivy-E are released anyway. I've got this one running at 4.5GHz with only a minor bump in voltage, and it really hauls ass at rendering videos and emulating anything I throw at it.