We spent New Years at Disney World a couple of years ago - it was amazing. Just a word of caution - we thought because it was going to be such a long day we would not leave for the parks until noon. Well by th etime we got there MK and Epcot were already full and they were not letting any more guests in. We ended up at MGM and it was a good time too. Plenty of bands and such. But MK and Epcot does have fireworks at around 8:00 for the kids but we were at MGM and they did not.
We also had no problems getting a bus to get where we needed to go. We were going to take a taxi until a couple of drivers got into a major fight over who was going to take us. My kids were scared and we decided neither cab was going to take us and off to the buses we went.