Also, wanted to add, I personally feel it's a must-see. It's just so cool. The music and the dancing, they pull people in to dance with them, confetti, etc. I actually saved a piece of the (mickey head shaped) confetti. Each float has a designated place on the route it stops, and the closer you are to one of those, the better.
However, they all run all over and switch floats, get wheeled around on bikes, etc so you still every character for a decent amount of time. You just see more of the ones that are on the float closest to you. It's a great way to get into the disney mood. Dh and I were lucky enough to walk in about 30 mins before it started, sat down right up front, and this was our first into to our vacation. It got us so excited and pumped up for the weekend!