I really can't say enough great things about this museum. It's among the very best I've seen, as a kid or a parent.
It's huge, with a variety of exhibits that will entertain/educate people of all ages. Among the attractions are "The Great Train Story," a scaled model railroad that simulates a journey from Seattle to Chicago; an actual 727; a working coal mine; and an actual German U-Boat from World War II. There are exhibits on genetics, storms, energy, etc., plus an Omnimax theater.
While we were there, the "Mythbusters" show had a special exhibit going.
I was also pleasantly surprised by the food court: It had a ton of options, including fresh salads, sandwiches to order, and pasta -- in other words, this wasn't just greasy junk food.
One word of caution: The museum *is* expensive. Some of the most popular parts of the museum -- the coal mine, the U-Boat, etc. -- require extra tickets, with set times. Particularly on more crowded days, you'll want to buy those tickets early and as part of a package.
Transportation: The museum is by the lake and south of downtown, near the University of Chicago/Hyde Park.
The easiest way to get there is to take the Metra Electric District trains, which is a commuter rail line that you can catch downtown at either the Millennium or Van Buren stations, each one a block from CTA-el lines. (The closest station to Millennium Station is closest to Randolph; the Van Buren Station is closest to Adams.) Once you get on the Metra, you go to the 55th/56th/57th Street station -- it's about 15 minutes. The museum is two blocks from the station -- you can't miss it.
Alternatively, you can take the CTA red or green lines to Garfield, then transfer to a city bus that will drop you at the door. We did the Metra route this time, the CTA-bus route last time. I thought the Metra was easier, but your mileage may vary.
Of course, you can also drive and park or take a cab.
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC