East Bank Club has a rooftop pool, though I'm not sure if you can get a guest pass without knowing a member.

If you want to chill outside and the obvious beaches are full, head to Lincoln Park--lots of green spaces are uncrowded. I often see people chilling out on the grass north of Diversey Harbor, and I'll head to green areas around Belmont Harbor.

Drinking isn't a requirement at places like ESPN Zone and Dave & Busters, but they can still be fun to hang out at.

Go to the movies?