Here's the situation: my brother and his family are planning a trip to Chicago August 6-8. They have already purchased Amtrak tickets are tickets to the Cubs game on August 7. They don't, however, have lodging and are struggling to find anything reasonably priced (less than $300/night) at a location that makes sense. Seems that all of the downtown hotels are booked -- must be something big going on that weekend. They aren't opposed to public transportation, in fact, plan on taking the red line to the game. Any suggestions of a reasonably priced, safe hotel near public transportation that is in a location that makes sense, especially since they will be arriving at Union Station?

Try Priceline

Priceline isn't a good option if more than one bed is needed. I may be wrong, but when the OP said "my brother and his family", I assumed there would be more than two people.

Lollapalooza is that weekend.

Rosemont (near O'Hare) has a station on the blue line. Maybe stay somewhere there and transfer to red line? Sorry, I'm not real familiar with Metra.

I don't know if this reply is to late or not, but I would suggest Hotwire. I am an avid Chicago visitor and use this site every time I go; in fact, I am planning a trip next weekend to Chicago and used Hotwire for my hotel and paid $89 a night for one of the Hilton hotels there. The only downfall is that you don't know the name before you book it but as long as you get an adequate star rating you will be fine. Also, you can call the hotel after you book the room(s) and ask for the appropriate number of beds (I have never had a problem getting the number of beds needed). This actually also applies to Priceline also.

Also, make sure to select the area you want to stay and hotwire is usually very close to the precise area you want to stay