where is a reasonable hotel near Wrigley field for a weekend series?

In addition to the Day's Inn mentioned by the other poster, there is a Best Western Plus Hawthorne Terrace Hotel located very close to Wrigley Field. It's at 3434 North Broadway.

Although we didn't stay at a hotel on our most recent pilgrimmage to Wrigley Field, we stopped near that Broadway area and had a quick bite to eat at Flub a Dub Chub's, which is at 3021 North Broadway. It's a no-frills basement restaurant where you can grab a Chicago style hotdog or hamburger and fries and eat outside on the tables located near the sidewalk. Great place to people watch and have a pleasant meal in the City. We ate there immediately before a Cubs game, and then walked off our meal as we headed north to watch the Cubs play at the Friendly Confines.

http://www.daysinn.com/hotels/illinois/chicago/day...

I stayed here a few years ago, its about 2 blocks from a subway station, says 4-9 min from Wrigley on google. enjoyed the area - nice shops, places to eat, but still a quiet area at night.