I have attended MVMCP in Dec. 2008 & MNSSHP in Oct. 2007, Sept. 2010 & Oct. 2011 (and again on Nov. 2, 2012), soooo, I can relay what I learned:
1. You can enter the park as early as 4 p.m. using your MVMCP tickets. There will be a special turnstile you will enter & then EVERYONE (even children under 3 who do not need a ticket) will receive a wristband. If you are already in the park, beginning around 5 or 6 p.m., signs will be put out in certain areas (especially down Main Street) indicating that there is a "party tonite" & guests with tickets can head to the front of the park or other areas to pick up a wristband. CM's try their best to escort non-party guests out of the park around 7 p.m., but don't be surprised to see some free-loaders. However, in order to ride rides, you must present your wristband to the attending queue CM, thus curbing the free-loaders from enjoying shorter ride times.
Another reason to enter the park earlier than 7 p.m., is to catch the "Castle Lighting Ceremony" around 6:30 p.m.. It's awesome & a great way to get your party started!!!
2. We like to watch ANY parade in MK in Frontierland: near the entrance to "Country Bear Jamboree." We prefer that side for viewing because if we need to make a semi-quick exit, we can stroll on thru the tunnels to Adventureland, plus it's close to the restrooms. Also, it seems to be less crowded here. We have tried other spots for viewing (Main Street, the Hub, the other side of the street in Frontierland, & across from "Sleepy Hollow" in Liberty Square), but this area is a tried & true favorite. Typically, we pick the first parade to watch, because we always have children in tow & in order to curb a meltdown, we leave the park by 10 p.m. (I know, I know, it's a crime to leave with only 2 hrs. to go). I have heard thru the grape vine that the second parade is less crowded, and that guests who view the 2nd parade ride as many rides as they can during the 1st parade.
3. The free cookies & cocoa are nothing to write home about (especially the cocoa), but hey, it's "free." We hit up the Tomorrowland Noodle Station for this.
4. Meet & Greets tend to have longer lines during special events because: A. They're dressed in holiday costumes. B. Rarer characters are out. C. Special photo opps are presented (i.e. Cinderella's carriage). Because we enter the park at 4 p.m., we can decide which character(s) we really, really want to meet, and then hang around the area that that character will be in around 7 p.m. . But the line for the "carriage" starts an hour or so before the official party time.
5. We really liked the "Celebrate the Season" castle show! You could conceivably stake out a spot around the Walt/Mickey Statue around 7:15 p.m., catch the 7:45 p.m. castle show & then wait for the 8:15 p.m. parade. Then spend the rest of your evening meeting characters & riding rides as the crowds start to thin out (depending on what night you go: the closer it is to Christmas, the longer the crowds stay). Orrrr...you could stake out that same spot around 9 p.m., watch the fireworks at 9:30 p.m., the castle show at 10:05 p.m. & wait for the 10:30 p.m. parade to come your way.
6. A fun & delicious way to start your party, make a reservation at the Liberty Tree Tavern! We did this in Dec. 2008, and it was like having Christmas dinner without the clean-up! Our ressie was at 5:15 p.m., which gave us enough time to eat to our hearts content & catch the 6:30 p.m. castle lighting ceremony!
Enjoy your trip and party!!