Well, it won't be days like in '00 (shudder as I remember), or like '04 where I was up all night. But here's Newsweek's analysis of when states close and when the media will probably call those states
Basically, the night could be over by 8 eastern time.
However, this article assumes the old notion, one that really caused problems in '00, which is each network wants to be the first to call a state. This election the media most likely will want to milk as much out of this as possible so look for the reverse to take place, as they wait until the last possible moment to call a state. They have all those fancy new gadgets, it'd be a shame to put them away after only 2 hours. I'd expect the first network to call the election around 10:30 or 11 barring any anything unforeseen.