I would take I-80 over US 30 along the southern edge of Chicagoland ANY day. As noted, 30 is a zoo, very busy road, lots of stoplights and traffic. Traffic on 80 is always busy but only really bad during rush hours, especially (heading west) on Sunday afternoons or M-F early AM (5-9).
IN Dunes SP has a very nice CG. Very popular, so you will need reservations on weekends and will probably want them for weeknights as well. It makes a good stop, either overnight or spending an extra day, along that route. I believe it's closer to I-94 than I-80, but still not bad, and probably better than other choices along I-80. In Illinois, southwest of the city, Starved Rock SP could also be a good stop, and not as far off I-80. Again, very popular; reservations a necessity on weekends. I think most of the sites at the Dunes have electric hookups; Starved Rock will be a mix of electric & non-electric sites.