The beach isn't up yet...I don't think.
The balloon is there.
The fair will be up.
Saturday is also Fete de la Musique, which is basically an all-night street music party. There will be some famous musicians playing at various spots around the city on stages, but there will also be tons of bands everywhere. It's a great day to just grab some beers and walk around sampling a bit of everything, stop into a few clubs and bars to see the acts, but also spend a lot of time on the street.
Here's a site so that you can see if any of the official acts would be something that you are interested in
David Guetta - Soirées
Hippodrome d'Auteuil - 75016 - Paris
If I didn't have to work I'd definately be there.