K.G.
The stations idea is great! Some things that have worked for me in the past with a wider age group:
Indoor kiddie pool filled with tissue paper (the kids have such a blast with that!)
"Fishing" game with fishing pole, sheets, and small toys
Bubbles
Big piles of pillows (just remind the older ones not to trample on the younger ones!)
Making pizza (kids add the toppings), decorating cookies, or playing with dough of any kind
Play-doh, coloring, stickers, etc.
Playing with puppets (maybe the older ones can make up a puppet show for the younger ones)
Above all, have fun!