I lived and worked in Chicago for 7 years (87-94). I loved it. Generally the North Side is going to be safer than the South Side. As you go North, things will get cheaper -- also, there has been lots of urban revitalization since I lived there and a lot of neighborhoods that were iffy when I lived there are now quite nice.

North of downtown, Lincoln Park is likely too expensive for a summer intern -- she should look at Wrigleyville, or Rogers Park.

Another option is to go all the way up to Evanston (where Northwestern University is). Lots of students leave for the summer so you might find a summer sublet from a student -- if I were you I'd have her check with the Northwestern housing office or student organization; probably a summer roommate program.

One advantage of Evanston is that she can get to the loop either via the CTA train (the El) or via the suburban commuter train, which passes through Evanston. At every el or train stop in Evanston there are apartments w/in walking distance of the train. Evanston is quite safe, and it gets her out of the city if she wants to do some bike riding on the weekend. Also, some pretty nice beaches, and a place to rent sailboats at the University.

Speaking of Northwestern, the Law School and Medical School for Northwestern are in the city -- maybe their housing offices would know of a student who needs a roommate for the summer?

BTW, Chicago in the summer is fantastic. Beaches, street festivals, etc. Great place to be!