Of course, I experience a draffic drop during the weekend, as well (about 20%, 40% and 30% on Friday, Saturday and Sunday, respectively). I agree that that's arguably due to people being at home and not at work. Yet, I've also noticed that publishing an article in the weekend (especially on Sunday) usually results in much more engagement in FB than on all other days of the week and easily outperforms content published in those days. So, my guess is that there is actually less people on the internet in the weekend, but that there is also much less people publishing on the internet; therefore, you get less organic traffic but you could potentially get more traffic from social networking.
Funny, when I was a cubicle rat, I would love holiday weeks (like that of the 4th) and weekends in general. Now as a publisher these last 13+ years, I dread holiday weeks (due to lower earnings/traffic) and weekends (for the same reason). My favorite days are Mondays because I get to go back to work!