I've always been a fan of EMH - especially during the holiday season.
When planning our days at the park, we usually go by:
- Reservations
- Parks with EMH
and then fill in the blanks with things we have not seen.
Every year, Magic Kingdom stays open until 3am the Friday after Christmas. While we are yet to make it until 3am, we normally hang around until 2am. Christmas week is the most crowded time of the year. During the day, we weave down Main Street avoiding floods of people filling the park.
There's a certain peacefulness to Main Street at 1am when barely anyone is left in the park. It results in amazing picture opportunities and rides with barely any wait time! We usually ride Barnstormer around 5 times - we once rode 11 consecutive times - the CMs were laughing watching me and my 29-year old sister get off the ride and get back in line.
So yes, I would recommend EMH. It really adds to the experience - especially during the most crowded time of the year... But if you're going to commit to EMH, go all out. Don't go to EMH and leave at 1am when it starts because it feels crowded - wait it out. By 1:30 the crowds will disperse.
Remember- a lot of people (during crowded times) go for the day. THey're locals that have the day off and they decide to spend the day in the park. Also, a lot of younger families vacation at Disney. By the end of the day, the one-day passes are ready to leave. The families hang around for the first showing of fireworks and parades and then head out. THis leaves the Disney diehards and older people in a seemingly empty park.