OT- Where to stay for Lollapalooza

So, I'm going to Chicago for Lollapalooza in August. I'm going half to celebrate my promotion I just got and half because Arcade Fire is going to be there and will rock your face off. I want some place awesome to stay. I'm not looking to do more than like 250/300 a night. I want something really close to Grant Park since I won't be bringing a car into the city proper. Also: any other advice anyone might give me on the transit system there? (time they shut down at night). Basically how its going to work is I'm going to drive to one of the Airports, leave a company car there, take the train in, do the lolla thing for the weekend, take the train back out and drive the rest of the way back to Detroit. Any and all advice/recommendations would be greatly appreciated.