How much time should I leave open to go to the aquarium and field museum?

I'd say about 4-8 hours total. Depends on what exhibits you want to see at both.

The shedd aquarium is going be quick

We usually spent 2-3 hours at the Shedd and 2-3 hours at the Field. It goes faster at the Shedd until they do the dolphin shows again.

I would allow the entire day. There is so much to see and do for both and you don't want to be rushed. Enjoy everything.

4hrs minimum. But it depends on how long you take to view items and what you want to see.

The aquarium was nice i loved it so did the kids. The 4D wasn't as cool as we were hoping for but. It is a short trip around. I would make it my 1st stop about an hour and a half, then 4+ hours at the field museum.

At least 8 hours @Regina Brooks

Depends on how much you want to see? If your first time, recommend setting aside at least an hour and a half for each with General Admission. Movies, Shows and Extra Exhibits add more time. So at least four hours between the two.

All day each

Thanks so much everyone!