Chicago Hotels-Best deal for convenient and safe places?

Hola! I figure plenty of folks on here have been heading to the greater Chicago area for business and school research. I will be heading there for a vacation of sorts, and I am curious if anyone has recommendations for reasonably priced (Say, less than $140 a night) hotels that are relatively central (no more than a 10 minute train ride from the "marvelous mile" or whatever it is called) and in a reasonably safe area. Bonus points for things that don't require a train/bus ride to get to things. Will be going mid-week in early june (tuesday-thursday night)
On priceline/hotwire we can find for about $140 a night for a hotel in "downtown", but as y'all are aware you don't find out the exact hotel until after you pay on those services!

Thanks for your help!