We arrived early for marathon weekend last year - on December 31. Just our youngest son and me - the rest of our family arrived later in the week.
It was wonderful. Flight landed, magical express, lunch at resort and then bus to DHS in the late afternoon. We had FP+, so that helped. He loved the dance party on the stage at DHS - yes, it was crowded, but really fun and he's a dancer so it was perfect for him. We had Jingle Bell Jingle Bam dessert party reservations, so that took us out of the crowd for a while - same could be accomplished by an ADR. After the JBJB fireworks at 9pm, he was ready to call it a night. Bus back to resort and we were asleep around 10:30pm, which was fine with me! I might have felt differently about NYE if we were in a park all day, if that park was Epcot or MK or if we stayed past the midnight fireworks and needed to use Disney transportation at that time. Our night was very low key and very fun - would absolutely do it again!