I80 has a short toll section where it is essentially part of the I294 tollway. I94 east into Indiana and Michigan is not toll.
US20 parallels I94 around southern Lake Michigan. It's ok, but has a fair amount of steel mill truck traffic. It's better if you stay on I94 to Michigan City, and take IN2 east to its junction with US20, and continue straight to South Bend. This is a route that SB residents take if they want to skip the tollway. I90 may be toll, but truck traffic is lighter than on I94.
US20 then runs as a freeway quality bypass around the south side of SB and Elkhart. Last fall they were working on US20 east of Elkhart, turning it into divided 4 lane. You take side trips in this area to the various Amish tourist traps. US31 is a new divided highway south from US20 bypass to US30 and beyond.