The whole park is practically a while picnic area. They have places with picnic tables, but there is also a ton of areas where you can just throw a blanket down and enjoy.
There are a few picnic benches but I really wouldn't recommend having a picnic there. If you go to the park either south or west in millennium park you would probably enjoy it better.
Yes there is more than 10 tables
Yes though not recommended
yes
Yes, there are open spaces where you can arrange for picnics.
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