Seeing all these responses, I think the key to most of these fixes is that we want to see the iconic movie moments we love happening in real-time on the floats. Floats like Ghostbusters and Jurassic Park are more evocative because there are a lot of action elements (though I wish that there were “streams” on the Ghostbusters float).
The most successful unit in memory in a parade is the Sleeping Beauty float in Festival of Fantasy, which tells the entire story of the battle between Phillip and Maleficent, including the fairies, the thorns, and the chaotic fire. The closest this parade gets is Jaws, with the active battle between the townies and Brody. The issue here is that the payoff float does not allow for the actor to truly activate the shark in any way.
I think that there are choreography changes possible that can allow the Delorian to “rev up” or “lightning to strike the clock tower”, E.T.’s magic healing touch to “activate”, and the “streams to cross” in an activated way, just as Excalibur is pulled in “Magic Happens” during every musical loop. They just need to find those story beats and find a way to activate at least one or two light/smoke effects on the floats to really make it feel like the films are alive.