If you're using a trailer type float, what if you replicated parts of your daycare onto the float? For example, set up a reading corner with stuffed animals, sensory box, an art corner, block corner, etc. Will your dcks be in it? Use lots of fun stuff and bright colors, have kids waving and smiling.
As far as what to give out, I like the pen idea, or magnets for their fridge. Do you have brochures to hand out? Or maybe tootsie roll pops with your card wrapped around it.
BUT if you're looking to have kids throw candy out, then just about any candy will do.
