Havent heard of any announcements yet about the entertainers, it is still a little early. Generally MGM will have a big name band, we saw Huey Lewis one year. Epcot has several bands including Beatlemania among others throughout the night as does MK. PI has a great party which requires a special admittance, which includes a dessert buffet and champagne. You may want to take a look at last years festiviites to get an idea at http://wdwig.com/nyeve.htm
If you decide to do one of the parks plan to arrive early and stay as the parks will fill to capacity and getting in later in the day is hit or miss.