adamxcl - 3:50 am on Sep 8, 2011 (gmt 0)
I see people leave conferences early on the last day all the time. Pubcon and others. Sometimes they leave in the second afternoon of a two day event. I then wonder why they bother with all the expense and if they took someone else's spot who would stay longer.
You will lose some people on the last day but I'll use last year just as an example. The last night had some great parties, hundreds of people to still meet and I am glad I stuck around as I met some additional great people.
This is one of, if not the best event of the year. The hotels are cheap. The conference is a good deal. Best to maximize it. I come in on Sunday to Friday and maximize every day. Use Twitter, the forum here (although not as active of a spot as I would like but that is because more and more attendees don't even know what webmasterworld is) to find others the entire week. You can just about always find someone to have a meal or drink during the whole week.
For the price of the hotel night, I'd stick around.