Being local, I've never stayed at either hotel. The Michigan Ave. location (Magnificent Mile) is probably better from a logistics standpoint. There's plenty to do within walking distance and you'll have access to the trolleys. The Ashland location is near the University of Illinois--Chicago campus. It's close to Taylor Street with great Italian restaurants and not far from Greek Town. There's nothing wrong with the neighborhood, and you can take the Blue Line elevated train to get to the Loop and Mag Mile. My guess is that if the upscale accomodations are more important than convenience, go with the Marriott. If you want to be able to get around easily, stay at the Courtyard.