The Derby in Arcadia would be one recommendation. Nice, old-school restaurant, themed toward the horse racing scene at nearby Santa Anita Racetrack. Good neighborhood, near Interstate 210 (the highway that runs direct to Rancho Cucamonga).
http://www.thederbyarcadia.com/
Assuming no material traffic, it's about a 50 minute drive. The most direct route would take you up the 110 (Arroyo Seco Parkway) to Pasadena, which is the oldest "freeway" in America. It's fun to see how engineers in the 1940's thought that scenic was more important than traffic flow.
If you do not want a place on the more upscale side like the Derby (since you will be towing a 4 year old), in Pasadena try Burger Continental. Despite the name it is primary Americanized Greek comfort food, has a great outdoor patio, and friendly staff.
http://www.burgercontinentalpasadena.com/home.html