This tip comes a bit late in the season since Halloween is right around the corner, but I attended MNSSHP at the Magic Kingdom last week, and I have a tip: eat dinner before you get to the park. A lot of the restaurants closed by the time the party started, so the few that were open were VERY crowded and had VERY slow service. I spent a good 20 minutes of my evening waiting in line at Cosmic Ray's. I wouldn't call this a complaint - all the servers were very apologetic and seemed to be doing their best, it was just an impossible situation because the park shut down too many of the restaurants for the party. If I attend that event in the future, I will definitely plan on eating a big meal outside of the park in the early evening! I wonder if this is also the case during the Christmas party and other events like that?
That being said, I had a great time at the party, because there was a dress rehearsal for New Fantasyland in progress! I ended up skipping all the "Halloween" festivities so I could hang out in the Fantasyland Forest all night. It was delightful, and I can't wait to return in 2014 when the Seven Dwarves Mine Train opens!