Cudahy:
Pulaski Park Pavillion, has various platforms and a playground close enough + stairwell.
By the lake: Off Lake Dr. and Ramsey Ave. follow the trail back, you'll see a dip leading to a sandy area, the dell here is pretty nice.
Kosciusko (Something super-Polish)? School, Has sever layer-edges, and a nice big-cast staircase.
Off of Ramsey Ave. is an unfinished Condo complex, the elevator shaft is still erected.
Public Library has very few waist-level ledges, good for a rainy-day, also has a small concrete wall good for vaults.
Behind the K-mart/ Sears Outlet is a truck-load drop, and some other fun suprises, definitely worth a look or two.
St. Francis:
The public Library has a fair bit of wall/ledge about it, cop stop is right across the street.
South Milwaukee:
Off 11th St. and Elm St. one block West of N. Chicago, is a bridge, just a bit further west is a path that goes into the woods, several bike jumps and trees here, easily useable for flip practice.
Seven bridges, has several dells which have stiarcases and paths on them, excellent for endurance training, build that cardio!
E. Milwaukee Ave. starting at 6th street, if you go westward you'll find several small spots good for just about whatever, especially the train station.
Sunrise Shopping Center (Strip-mall), the area behind it is excellent for wall-work.
Bayview:
Behind Outpost natural Foods, post-10PM is an excellent practice wall, it has a lead-up as well.
Across the street is KK park, has a pretty fun wall here, the restroom pavillion can be fun if you work on it correctly.
Humboldt park Ampitheatre, the stage has two stair sets, and the stage is a stair too.
Milwaukee, if you follow the Milwaukee River Walk-way, you can find some beautiful pots, particularly around the statues.