As for me, I went on NYE to both MK & Epcot. Very easy to do, park hopping wise, especially with the monorail in play.
Some tips about park hopping on NYE I would give:
- Plan ahead, plan ahead, PLAN AHEAD! Make your FPs 60 days in advance, and plan to stay on-site! Make your ADRs as soon as possible!
- Take advantage of extra magic hours (especially when MK does them in the morning!) Better yet, start at the park offering EMH and hop to the next one as soon as you can!
- Be ready to adjust your plans on the fly left and right!
- And just know that it will be very busy!
I started at MK for AM EMH did 7DMT, then knocked down Splash Mountain at RD and immediately after hopped over to Epcot for the majority of the day, starting with SSE (w/ FP+), then Mission Space Green (30 min posted, actual about 25), and then did Soarin' (w/ FP+). Made it to the China pavilion for lunch at Nine Dragons, then saw Reflections of China - before then I attempted to do Gran Fiesta Tour, but skipped due to the long wait. One of my friends from college was there, and he wanted to meet me at Test Track. I waited and he came off, I decided I was intending to do Single Rider on Test Track, but he was against it (it was posted 120 minutes!) We decided to walk around World Showcase together and hang out a bit.
I met his family for dinner at San Angel Inn before heading out to see Epcot Forever (which IMHO is a good start but overall is MEH). After that I left Epcot and that's when I got word that MK was back open. Made back to MK w/out trouble, decided to reride Splash Mountain (which was posted at 80 mins for standby), and snagged a FP+ for Thunder Mountain. Checked out some of the Festivities in Frontierland and went to the confectionary to grab a cookie - Main St was packed and they were alerting people via MDE that Main Street was at capacity and to view Fantasy in The Sky from Frontierland, Tomorrowland, or Fantasyland. I loved Fantasy In The Sky, great way to ring out 2019 and ring in 2020! Then I did Pooh and Haunted Mansion with very little wait (30 minutes and 30 seconds respectfully).
I will admit while it was a chaotic exodus, Disney had their A-game down that night with buses back to AOA one after another.