I think the mosaic designs are wonderful! They're very playful, bright, and I think children will enjoy them quite a bit.
It's too bad that Super Playground event conflicts with the brand new Riverview Park Heritage Day festival. I live in and am an advocate of Highland Park, but this is a big day for Riverview Park, and they have really put together a great group of (free) events for tomorrow:
http://www.city.pittsburgh.pa.us/parks/html/riverview_park_heritage_day.html
So, if you get a chance after the Super Playground Event, stop up at Riverview Park for the Heritage Day, it looks like it will be great!