I'm out of the loop on most Chicago spots these days, but those I knew which were close to Metra or CTA stops are either sealed or demoed... some just this year. DS also has had security for a few years after turning into a tourist trap
, where supposedly people were either getting killed or having to be rescued. They sit by the gate but sometimes patrol. Some still go to view the low-rise graffiti building, but to me it's not worth it anymore.
I hopped the South Shore trains to Gary for years and never had issues walking alone to the bigger spots, sometimes I took the bus from the Metro Center for stuff further away. Walk along the main roads and avoid going into the neighborhoods (Emerson, especially) for as long as you can, until you're about parallel to the spot. S&B is walkable, and you're along the highway the entire time. Either way, def hit stuff there while you can as the city wants most of it torn down soon, and is slowly beginning to act on it.