Other Car Rental Programs/Partners (ie. Alamo, Enterprise, Sixt) - Chicago Offsite For Weekly Deals?

Planning vacation trip that will start and end in Chicago. Will need car for two weeks. Still have some date flexibility. My preliminary investigation shows offsite Enterprise locations several miles from O’Hare or even downtown have weekly rates significantly below airport. Can use other companies than Enterprise. What experiences have you had doing this? Pitfalls to avoid?

Thanks for any comments.

Try to pick something that's not too far from the blue line CTA train. Be prepared for about a 30-45 minute ride on the train to downtown. Be sure to factor in the cost of a taxi if you can't take the train. Also, off site locations usually have limited hours, especially on the weekend.