From what I've heard, those Mackies are probably the standard when looking at powered studio speakers. There are some that are supposed to be 'better', such as the higher end Genelec's, but the prices go up real quick. At that price point, I don't think there is anything better.. not that I make it a habit of listening to many powered studio monitors of course..
As for prettying them up, a new grill might make them nicer, but (at least for me) the thing that kills is that they only come in the black faux-wood vinyl wrap. For whatever reason, that "look" is just awful to me.
JCD