Respectfully I have to disagree with the above poster. Just my opinion, one of very many on here!
I've done MVMCP multiple times and the crowds get bigger every year which is tiring in itself.
I'm a HUGE fan of MVMCP and would go every year. I tend to stay until the very end, just love walking out Main Street with the Christmas music.
The photopass photographers are still out, a great opportunity to get some incredible pics.
If you like parades, this is one not to be missed. I love Santa and the toy soldiers. I've never had a problem getting a great seat close to the start of the second parade, especially in Frontierland.
Fireworks can be seen from Frontierland, but really the castle projections are best viewed from Main Street.
Hot chocolate, cider and cookies give my feet a break and allow me to stop, breathe, people watch and just immerse myself.

And allow the crowds after the fireworks to disperse a bit.
If you like characters, this is the only one time I know you can get all 7 dwarves in one pic. In 2015, the handler was losing patience, jokingly, as the dwarves wouldn't stop teasing me. Goofy, Happy and Bashful were in cahoots together.
It's a long line, but for me,the pics & memories are pricesless. In fact all the character interactions were outstanding. Goofy stole my sweater and played keep-away with Pluto.
If you're not into parades, a perfect time for attractions, shorter lines, fireworks from the astro orbiter, or top of Splash Mountain as well as the perimeter fireworks, wow.
The shows are exceptional, and you will be criss-crossing the park quite a bit, due to scheduling.
One tip, if you feel like it, get matching t-shirts from Zazzle (can I say the company name?), they have great customizable Christmas Disney shirts. I've done it 5 times for 2 people to 8. We got so much positive feedback from CMs, and guests, even the next day on the monorail when a family literally squealed in recognition. That's amazing, considering the amount of people there!
Photopass photographers love it, and take more shots. I went up for cookies and hot chocolate at a slow booth, and the CM called over all the over CMs, and I had to do a pirouette for all of them. Don't worry I was the only person at the counter. They all told me they love it when the guests really get in the spirit too.
And, the coup de grace, your MVMCP ticket gets you in MK at 4 pm, 3 hours before the official start of the party.
Even with a mid-day break, I really think it's pushing it to do MK during the day and MVMCP the same night.
If you've never been to the party, it can be a lot to take in.
I go for the decorations, the fireworks, the shows, character interactions, the PARADE, and the merchandise you can only get during the party.
If you want to get in the mood early, go to a late lunch or early dinner at Chef Mickey's the day of the party while wearing your shirts. If not to your liking, try Casey's in MK, score if you can get an outside table before the fireworks.
I love walking out an almost empty Main Street, with CMs in front of the big tree, holding signs "See Ya Real Soon."
Oh, there are some really magical character pic opportunities with the Fab 5 on your way out.

Perhaps you have waaay more energy

than I, but I have never woken up before noon the day after MVMCP. Plan a resort, maybe laundry/pool day, I need it, chances are you will too.
And it's so worth it. I've done it 5 times and can't wait to (hopefully) go again this year.
Any particular reason? Disney and Christmas, it's not just for kids.
Please feel free to post or pm me with any specific questions. I've learned so much from the Dis,

I love sharing my experiences. Which may not match others, but that's just one of the wonders of Disney!
