Surprisingly, Disney songs can get really difficult (except for the love ones, lol). For really little kids, I like to use "super simple songs" or "dream English kids" songs from youtube. Most of them have subtitles and they also have motions (so the kids can dance at the same time). This really keeps their interest, imho. I also usually give points to the best team (participation-based) to really motivate them, lol.
For older kids, I recommend using "doodle songs" on youtube. BUT! Definitely listen to them all the way through before using them because, despite the fact that they were drawn by kids (so you would think the songs would be fine), there are some questionable ones like "The Lazy Song" by Bruno Mars x.x
My students also like Connie Talbot's "I have a dream," because it's pretty easy and they all like her because she is around their age in the video ^.^
Good luck!