Umm..im aware that hours billed is different from hours worked. If you go to nalp it shows both. According to nalp you work 2300 hours tops and make 160,000 at the big firms. That's less than 50 hours a week. That hardly seems like the long/hard hours everyone says big law requires.
I doubt Monday morning would be a problem. Let's be realistic here. If these are BIGLAW firms, odds are, many of the people you're meeting with spent a chunk of their weekend working anyway. Mondays sort of loose their dreadfulness when you no longer get to play and screw around for a full 48 hours on the weekend.