Good decision.
We attended the NYE party one year ago and were very dissapointed. Seemed as if lots of day guests without party tickets stayed to watch the special Parade and Fireworks (for parade we lined up an hour before to get decent view ).
Fireworks were totally screwed up for me because the matching music was only piped in on Main street and in front of castle. We were at the entrance to Discoveryland next to the shop called Constellations and got the "normal" Discoveryland-music there.
To all that go: Line up very early for parade and fireworks and prepare for children on shoulders - even in front of people in wheelchairs (I was shocked! People were so rude and selfish).
We won't go any more.