The Clubhouse for spectacular brunch (Sundays only):
http://www.theclubhouse.com/Oakbrook/brunch.cfm
Egg Harbor in Hinsdale (much superior to the Yorktown location, which is possibly closer):
777 N. York
Hinsdale, IL 60521
Phone: 630-920-1344
On the corner of Ardmore and Roosevelt (north on 83 from the shopping center, then west on Roosevelt Road) are Simon's and Kappy's, owned by the same family and both typical American diner fare.
On 83 and St. Charles is Kopper Kitchen, very good Belgian Waffles and Greek diner food. All of these last three options are extremely casual and nothing special (just solid breakfast food).